Combine all integTest workflows into 2 workflow runs

- Workflow to run all integTest workflows, allowing use of prior cache entries
- Workflow that starts with empty cache

Both of these use workflow_call to combine the existing workflows.

.github/workflows/integ-test-execution-with-caching.yml

@@ -0,0 +1,45 @@
+name: Test save/restore Gradle Home with direct execution
+
+on:
+  workflow_call:
+    inputs:
+      cache-key-prefix:
+        type: string
+  workflow_dispatch:
+
+env:
+  GRADLE_BUILD_ACTION_CACHE_KEY_PREFIX: execution-with-caching-${{ inputs.cache-key-prefix }}
+  GRADLE_BUILD_ACTION_CACHE_DEBUG_ENABLED: true
+
+jobs:
+  seed-build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@v2
+    - name: Execute Gradle build
+      uses: ./
+      with:
+        build-root-directory: .github/workflow-samples/groovy-dsl
+        arguments: test
+
+  # Test that the gradle-user-home is restored
+  verify-build:
+    needs: seed-build
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@v2
+    - name: Execute Gradle build
+      uses: ./
+      with:
+        cache-read-only: true
+        build-root-directory: .github/workflow-samples/groovy-dsl
+        arguments: test --offline -DverifyCachedBuild=true
+