Editor: Bump pinned hash for the Gutenberg repository.

This updates the pinned hash from the `gutenberg` from `e2970ba736edb99e08fb369d4fb0c378189468ee ` to `c15cef1d6b07f666df28dac0383bafb0edfe0914`.

The following changes are included:

- RTC: Predefined retry schedules for disconnect dialog, make more lenient (https://github.com/WordPress/gutenberg/pull/76966)
- Block Editor: Prevent Enter key from inserting paragraphs in contentOnly sections (https://github.com/WordPress/gutenberg/pull/76989)
- Cover block: fix embed video background Error 153 in editor (https://github.com/WordPress/gutenberg/pull/76904)
- Restore original template registration tests alongside activation variants (https://github.com/WordPress/gutenberg/pull/77068)
- Avoid stale values in core/cover block for RTC compatibility (https://github.com/WordPress/gutenberg/pull/76916)
- Bump oras-project/setup-oras (https://github.com/WordPress/gutenberg/pull/77096) (https://github.com/WordPress/gutenberg/pull/77110)
- RTC: Change SyncConnectionModal to isSyncConnectionErrorHandled filter and drop IS_GUTENBERG_PLUGIN check (https://github.com/WordPress/gutenberg/pull/76853)
- contentOnly template lock: Fix block insertion and removal rules (https://github.com/WordPress/gutenberg/pull/77119)
- Global Styles Revisions: Fix footer overflow (https://github.com/WordPress/gutenberg/pull/77103)
- Revision: Fix 'Show changes' button reset state (https://github.com/WordPress/gutenberg/pull/77122)
- Link picker: Decode HTML entities in link preview title (https://github.com/WordPress/gutenberg/pull/77170)
- Connectors: don't clobber third-party custom render in registerDefaultConnectors (https://github.com/WordPress/gutenberg/pull/77116)
- Connectors: Replace speak() with notice store for state changes (https://github.com/WordPress/gutenberg/pull/77174)
- Core Data: Fix 'useEntityProp' for raw attributes (https://github.com/WordPress/gutenberg/pull/77120)
- Fix PatternsActions prop name from postType to type (https://github.com/WordPress/gutenberg/pull/77251)
- Fix: restore editor canvas padding in classic themes (https://github.com/WordPress/gutenberg/pull/76864)
- RTC: Add filterable flag for meta box RTC compatibility (https://github.com/WordPress/gutenberg/pull/76939)
- Fix failing 'WP_HTTP_Polling_Sync_Server' unit test (https://github.com/WordPress/gutenberg/pull/77025) (https://github.com/WordPress/gutenberg/pull/77325)
- Edit Post: Fix warning in 'useMetaBoxInitialization' hook (https://github.com/WordPress/gutenberg/pull/77311)
- Update the page slug we link to for the AI plugin after the plugin has been installed and activated (https://github.com/WordPress/gutenberg/pull/77336)
- Test: Connectors Point to the righ page. (https://github.com/WordPress/gutenberg/pull/77272)
- Post Editor: Store metaboxes RTC-compatible flag on location entries (https://github.com/WordPress/gutenberg/pull/77361)
- Core Abilities: Export initialization promise as `ready` (https://github.com/WordPress/gutenberg/pull/77254)
- Block Editor: Strip per-block custom CSS on save for users without edit_css (https://github.com/WordPress/gutenberg/pull/76650)
- Add heading level 1 for the fonts page (https://github.com/WordPress/gutenberg/pull/77482)
- Connectors: Treat network-active plugins as active in plugin status check (https://github.com/WordPress/gutenberg/pull/77661)
- RTC: Fix disconnect dialog due to uneditable entity (https://github.com/WordPress/gutenberg/pull/77242)
- RTC: Fix "Connection Lost" dialog when too many entities are loaded (https://github.com/WordPress/gutenberg/pull/77631)
- RTC: Fix "Edit as HTML" content reset during collaboration (https://github.com/WordPress/gutenberg/pull/77043)
- RTC: Add optional `shouldSync` function to entity sync config (https://github.com/WordPress/gutenberg/pull/76947)
- RTC: Fixed orphaned meta causing dirty editor state (https://github.com/WordPress/gutenberg/pull/77529)
- Ensure "Retry" button is stable during retries (https://github.com/WordPress/gutenberg/pull/77234)
- Patterns: add confirmation dialog before disconnecting/detaching (https://github.com/WordPress/gutenberg/pull/75713)
- Template parts: make 'Detach' context menu item consistent across patterns and template parts (https://github.com/WordPress/gutenberg/pull/77581)
- Remove sandbox `allow-same-origin` for core/html blocks (Merge https://github.com/WordPress/gutenberg/pull/77212 to `wp/7.0`) (https://github.com/WordPress/gutenberg/pull/77699)
- Added Context for Next/Prev Enlarge Image (https://github.com/WordPress/gutenberg/pull/76967)
- Backport: Writing Flow: fix arrow keys skipping paragraph containing link (https://github.com/WordPress/gutenberg/pull/77478)
- Revisions: Improve screen reader accessibility for diff markers region and slider (https://github.com/WordPress/gutenberg/pull/77660)
- Connectors: Add role="list" wrapper to connector cards for valid ARIA structure (https://github.com/WordPress/gutenberg/pull/77689)
- Command Palette: Fix macOs label for sites unable to determine UA via PHP (https://github.com/WordPress/gutenberg/pull/77638)
- RTC: Fix inline inserter reset on update sync (https://github.com/WordPress/gutenberg/pull/76980) (https://github.com/WordPress/gutenberg/pull/77706)
- Connectors: keep focus on action Button during install (https://github.com/WordPress/gutenberg/pull/77544)
- Added Translator Context for Reply (https://github.com/WordPress/gutenberg/pull/77891)
- Editor: Improve revisions diff pairing performance (https://github.com/WordPress/gutenberg/pull/77126)
- Core Data: Treat single-item responses specially (https://github.com/WordPress/gutenberg/pull/76318)
- Site editor: preserve non-global styles in pattern previews (https://github.com/WordPress/gutenberg/pull/77957)
- RTC: Fix divergence when two offline users reconnect (https://github.com/WordPress/gutenberg/pull/77980)
- RTC: Fix compaction unit test (https://github.com/WordPress/gutenberg/pull/77986)
- Connectors: Stop e2e capability restriction from leaking across specs (https://github.com/WordPress/gutenberg/pull/77857)
- Connectors: Clarify AI plugin callout copy (https://github.com/WordPress/gutenberg/pull/78043)
- Fix: Only auto register settings if the plugin the connector references is installed and active. (https://github.com/WordPress/gutenberg/pull/77273)
- Connectors: Add is_active callback support to plugin registration (https://github.com/WordPress/gutenberg/pull/77897)
- RTC: Fix race condition on room creation which can cause a split update log (https://github.com/WordPress/gutenberg/pull/77675)
- RTC: Fix find_canonical_storage_post_id() always returning null (https://github.com/WordPress/gutenberg/pull/78053)
- i18n: add context to scale (https://github.com/WordPress/gutenberg/pull/76917)
- Revisions: Simplify fetching (https://github.com/WordPress/gutenberg/pull/77086)
- e2e: Add e2e tests for template and template part revisions (https://github.com/WordPress/gutenberg/pull/76923)
- Editor: Paginate revisions slider by 100 per page (https://github.com/WordPress/gutenberg/pull/77200) (https://github.com/WordPress/gutenberg/pull/78070)
- Revisions: Add diagonal stripe patterns to diff markers to avoid color-only distinction (https://github.com/WordPress/gutenberg/pull/77904)
- Revision: Fix failing e2e test (https://github.com/WordPress/gutenberg/pull/78079)
- Real-time collaboration: Bundle @wordpress/sync instead of exposing as wp.sync (https://github.com/WordPress/gutenberg/pull/78085)

A full list of changes can be found on GitHub: https://github.com/WordPress/gutenberg/compare/e2970ba736edb99e08fb369d4fb0c378189468ee…c15cef1d6b07f666df28dac0383bafb0edfe0914.

Log created with:

git log --reverse --format="- %s" e2970ba736edb99e08fb369d4fb0c378189468ee..c15cef1d6b07f666df28dac0383bafb0edfe0914 | sed 's|#\([0-9][0-9]*\)|https://github.com/WordPress/gutenberg/pull/\1|g; /github\.com\/WordPress\/gutenberg\/pull/!d' | pbcopy

See #64595.

git-svn-id: https://develop.svn.wordpress.org/trunk@62333 602fd350-edb4-49c9-b593-d223f7449a82