build: inline external Github Actions to unblock CI (#12241)

* build: inline cached-dependencies to unblock CI

* Run E2E on pull_request on;y

* Inline all external actions

* Checkout needed for internal actions

Also fixes pre-commit

* Add missing files

.github/actions/comment-on-pr/action.yml

@@ -0,0 +1,15 @@
+name: Comment on PR
+author: Aaron Klaassen <aaron@unsplash.com>
+description: Leaves a comment on an open PR matching a push event.
+branding:
+  icon: 'message-square'
+  color: 'blue'
+inputs:
+  msg:
+    description: Comment's message
+    required: true
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+  args:
+    - ${{ inputs.msg }}