Migrate Travis to GitHub Actions for unit tests and set up code cover…

…age (#439)

* Migrate to GitHub Actions and set up code coverage
* fetch-depth: 2

app-maven-plugin/.github/workflows/unit-tests.yaml

@@ -0,0 +1,38 @@
+name: Unit Tests
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  unit-tests:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        java: [8, 11]
+    env:
+      CLOUDSDK_CORE_DISABLE_USAGE_REPORTING: true
+      CLOUDSDK_CORE_DISABLE_PROMPTS: true
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: ${{ matrix.java }}
+      - uses: actions/cache@v2
+        with:
+          path: ~/.m2/repository
+          key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
+          restore-keys: |
+            ${{ runner.os }}-maven-
+      - name: Run tests
+        run: |
+          mvn -B -U --fail-at-end clean verify
+      - name: Test Coverage
+        uses: codecov/codecov-action@v1
+        with:
+           name: actions ${{matrix.java}}