[Build] Collect frontend code coverage from Cypress tests (#9555)

* build: collect code coverage from Cypress

Collect frontend code coverage reports from Cypress tests and add
proper tagging for all tests.

* Fix bash script lint error from shellcheck

* Revert Cypress to 4.3.0 to see if it fixes a failing test

.github/workflows/superset-frontend.yml

@@ -6,13 +6,11 @@ jobs:
   frontend-build:
     name: build
     runs-on: ubuntu-18.04
-    env:
-      CI: github-actions
     steps:
     - name: Checkout code
       uses: actions/checkout@v2
     - name: Install dependencies
-      uses: apache-superset/cached-dependencies@ddf7d7f
+      uses: apache-superset/cached-dependencies@adc6f73
       with:
         run: npm-install
     - name: eslint
@@ -26,4 +24,4 @@ jobs:
     - name: Upload code coverage
       working-directory: ./superset-frontend
       run: |
-        bash <(curl -s https://codecov.io/bash) -cF unittest,javascript
+        bash <(curl -s https://codecov.io/bash) -cF javascript