InlineChatIntent (#1549)

* remove references to old setting `github.copilot.chat.advanced.inlineChat2`

* play with `InlineChatIntent`

* wip

* move things, better/simpler prompt

* cleanup, renames, stuff

* more wip

* done after tool call

* edit and generate stest for new InlineChatIntent

* use codebook for diagnostics

* inline chat fixing stests

* stest run

* remove old Inline2 tests

* remove slash commands for v2, remove the editCodeIntent path for v2

* :lipstick:

* :lipstick:

* Don't use `diagnosticsTimeout` when with inline chat because the new diagnostics will never be read but slow down the result

* fix compile error

* stest run

* update baseline

* prevent some JSON errors from empty output

* unfresh baseline.json

* use `MockGithubAvailableEmbeddingTypesService` in stests

* back to hamfisted skipping of stests

* send telemetry from inline chat intent

* tweak some stests