extension_ci: Merge extension workflow files into one file (#48810)

This PR consolidates the two workflow files shipped to extensions into
one, which stops us from requiring a separate runner for what can
actually be done in one workflow.

It also
- adds a check that version bumps will now only be created by zed-zippy
in separate commits.
- Makes the bumping of versions faster and more reliable.
- (Hopefully) fixes an issue we were seeing in some CI tests.

Release Notes:

- N/A

extensions/workflows/shared/release_version.yml

@@ -1,19 +0,0 @@
-# Generated from xtask::workflows::extensions::release_version within the Zed repository.
-# Rebuild with `cargo xtask workflows`.
-name: extensions::release_version
-on:
-  push:
-    tags:
-    - v**
-jobs:
-  call_release_version:
-    permissions:
-      contents: write
-      pull-requests: write
-    uses: zed-industries/zed/.github/workflows/extension_release.yml@main
-    secrets:
-      app-id: ${{ secrets.ZED_ZIPPY_APP_ID }}
-      app-secret: ${{ secrets.ZED_ZIPPY_APP_PRIVATE_KEY }}
-defaults:
-  run:
-    shell: bash -euxo pipefail {0}