github: add CI workflow

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

.github/ci-gradle.properties

@@ -0,0 +1,9 @@
+org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8 \
+                   --add-opens jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED \
+                   --add-opens jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
+                   --add-opens jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
+                   --add-opens jdk.compiler/com.sun.tools.javac.jvm=ALL-UNNAMED  \
+                   --add-opens jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
+                   --add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED \
+                   --add-opens jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
+                   --add-opens jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED

.github/workflows/pull_request.yml

@@ -0,0 +1,56 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  run-unit-tests:
+    runs-on: ubuntu-latest
+    steps:
+
+    - uses: actions/setup-java@d9126d7df2f1b080b603441eaf5810ced3614e78
+      with:
+        distribution: 'zulu'
+        java-version: '16'
+
+    - name: Checkout repository
+      uses: actions/checkout@5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f
+
+    - name: Copy CI gradle.properties
+      run: mkdir -p ~/.gradle ; cp .github/ci-gradle.properties ~/.gradle/gradle.properties
+
+    - uses: burrunan/gradle-cache-action@03c71a8ba93d670980695505f48f49daf43704a6
+      name: Run unit tests
+      with:
+        arguments: test --stacktrace
+
+    - name: (Fail-only) upload test report
+      if: failure()
+      uses: actions/upload-artifact@27bce4eee761b5bc643f46a8dfb41b430c8d05f6
+      with:
+          name: Test report
+          path: app/build/reports
+
+  stylecheck:
+    runs-on: ubuntu-latest
+    steps:
+
+    - uses: actions/setup-java@d9126d7df2f1b080b603441eaf5810ced3614e78
+      with:
+        distribution: 'zulu'
+        java-version: '16'
+
+    - name: Checkout repository
+      uses: actions/checkout@5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f
+      with:
+        fetch-depth: 0
+
+    - name: Copy CI gradle.properties
+      run: mkdir -p ~/.gradle ; cp .github/ci-gradle.properties ~/.gradle/gradle.properties
+
+    - uses: burrunan/gradle-cache-action@03c71a8ba93d670980695505f48f49daf43704a6
+      name: Check codestyle with Spotless
+      with:
+        arguments: spotlessCheck