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/workflows/superset-frontend.yml

@@ -6,14 +6,10 @@ jobs:
   build:
     runs-on: ubuntu-18.04
     steps:
-      - name: Cancel Previous Runs
-        uses: styfle/cancel-workflow-action@0.6.0
-        with:
-          access_token: ${{ github.token }}
       - name: Checkout code
         uses: actions/checkout@v2
       - name: Install dependencies
-        uses: apache-superset/cached-dependencies@b90713b
+        uses: ./.github/actions/cached-dependencies
         with:
           run: npm-install
       - name: lint