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/actions/check_style/action.yml

@@ -4,12 +4,11 @@ description: "Checks code formatting use cargo fmt"
 runs:
   using: "composite"
   steps:
+    - name: Check for Typos with Typos-CLI
+      uses: crate-ci/typos@v1.24.6
+      with:
+        config: ./typos.toml
+
     - name: cargo fmt
       shell: bash -euxo pipefail {0}
       run: cargo fmt --all -- --check
-
-    - name: Find modified migrations
-      shell: bash -euxo pipefail {0}
-      run: |
-        export SQUAWK_GITHUB_TOKEN=${{ github.token }}
-        . ./script/squawk