ci(e2e): configure applitools intergration

Configure Cypress E2E tests to upload results to applitools,
if the APPLITOOLS_API_KEY GitHub Actions secret is available.

If this secret is unavailable, then Applitools is not used.

.github/workflows/e2e.yml

@@ -5,6 +5,10 @@ on: [push, pull_request]
 permissions:
   contents: read
 
+env:
+  # on PRs from forks, this secret will always be empty, for security reasons
+  USE_APPLI: ${{ secrets.APPLITOOLS_API_KEY && 'true' || '' }}
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -32,7 +36,26 @@ jobs:
       - name: Run Build
         run: yarn build
 
+      - if: ${{ env.USE_APPLI }}
+        name: Notify applitools of new batch
+        # Copied from docs https://applitools.com/docs/topics/integrations/github-integration-ci-setup.html
+        run: curl -L -d '' -X POST "$APPLITOOLS_SERVER_URL/api/externals/github/push?apiKey=$APPLITOOLS_API_KEY&CommitSha=$GITHUB_SHA&BranchName=${APPLITOOLS_BRANCH}$&ParentBranchName=$APPLITOOLS_PARENT_BRANCH"
+        env:
+          # e.g. mermaid-js/mermaid/my-branch
+          APPLITOOLS_BRANCH: ${{ github.repository }}/${{ github.ref_name }}
+          APPLITOOLS_PARENT_BRANCH: develop
+          APPLITOOLS_API_KEY: ${{ secrets.APPLITOOLS_API_KEY }}
+          APPLITOOLS_SERVER_URL: 'https://eyesapi.applitools.com'
+
       - name: Run E2E Tests
         run: yarn e2e
         env:
           CYPRESS_CACHE_FOLDER: .cache/Cypress
+          # Mermaid applitools.config.js uses this to pick batch name.
+          APPLI_BRANCH: ${{ github.ref_name }}
+          APPLITOOLS_BATCH_ID: ${{ github.sha }}
+          # e.g. mermaid-js/mermaid/my-branch
+          APPLITOOLS_BRANCH: ${{ github.repository }}/${{ github.ref_name }}
+          APPLITOOLS_PARENT_BRANCH: develop
+          APPLITOOLS_API_KEY: ${{ secrets.APPLITOOLS_API_KEY }}
+          APPLITOOLS_SERVER_URL: 'https://eyesapi.applitools.com'