ci: Improve GitHub Action modularity (#18861)

- Closes: https://github.com/zed-industries/zed/issues/19351
- Switch to using the official [typos GitHub Action](https://github.com/crate-ci/typos/blob/master/docs/github-action.md)
- Move the typos check into `actions/check_style`
- Move Squawk Postgres migration check out of `actions/check_style` file into ci.yml
- `actions/check_style` can now be run on stateless/linux runners (previous required self-hosted MacOS runner)
- ci.yml: Split old `style` into checks into those that can run statelessly (linux) and everything else into a new `migration` group which benefit from the full git checkout available on the MacOS runners.
- ci.yml: Move `Check unused dependencies` from style to `linux_tests`
- Add `if: github.repository_owner == 'zed-industries'` to all jobs so they won't try and run on GitHub forks.

.github/workflows/docs.yml

@@ -11,6 +11,7 @@ on:
 jobs:
   check_formatting:
     name: "Check formatting"
+    if: github.repository_owner == 'zed-industries'
     runs-on: ubuntu-latest
 
     steps:
@@ -29,5 +30,8 @@ jobs:
             false
           }
 
-      - name: Check spelling
-        run: script/check-spelling docs/
+      - name: Check for Typos with Typos-CLI
+        uses: crate-ci/typos@v1.24.6
+        with:
+          config: ./typos.toml
+          files: ./docs/