Apply path filtering checks to test-all workflow (#55429)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/55429

Completes this stack of diffs focused around the organisation and efficiency of the `test-all` GitHub Actions workflow.

**Changed**

All root jobs (excluding `lint`), when running against a PR, now depend on the initial `check_code_changes` job. This matches any non-Markdown, non docs change — meaning trivial PRs such as changelog updates should now avoid unnecessarily running the expensive parts of this workflow.

IMPORTANT: This is a significant change at the root of the workflow that contributes to our prebuilts/release infra — please review carefully.

**The new `any_code_change` filter**

Extremely defensive:
- Matches `'!**/__docs__/**', '!**/*.md'` only.
- Also **always** sets `any_code_change` to true if on `main`, a release branch, or on a workflow dispatch (`github.event_name != 'pull_request'`).

Changelog: [Internal]

Reviewed By: cortinico

Differential Revision: D92417918

fbshipit-source-id: ca5bc41a3c11569b8f69062ab66eeeab89d30089