ci: basic frontend and backend CI pipeline

Add basic frontend and backend CI workflows which acts on push and pull
requests. The workflows are only triggered for changes in their
respective directories.

.github/workflows/backend.yml

@@ -0,0 +1,41 @@
+name: Build Backend
+
+# We want this workflow to be only triggered for changes to the backend
+on:
+  push:
+    paths:
+      - './backend/**'
+  pull_request:
+    paths:
+      - './backend/**'
+
+jobs:
+  build-backend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./backend
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up JDK
+      uses: actions/setup-java@v3
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+        cache: maven
+    - name: Set up Maven
+      uses: stCarolas/[email protected]
+      with:
+        maven-version: 3.8.6
+    # Compile and run unit and integration tests
+    - name: Build
+      run: mvn -B verify --file pom.xml
+    - name: Use Node.js
+      uses: actions/setup-node@v3
+      with:
+        node-version: ${{ matrix.node-version }}
+        cache: 'npm'
+    - run: npm ci
+    - run: npm run build --if-present
+    - run: npm test
+

.github/workflows/frontend.yml

@@ -0,0 +1,23 @@
+name: Build Frontend
+
+# We want this workflow to be only triggered for changes to the frontend
+on:
+  push:
+    paths:
+      - './frontend/**'
+  pull_request:
+    paths:
+      - './frontend/**'
+
+jobs:
+  build-frontend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./frontend
+    steps:
+    - uses: actions/checkout@v3
+    - run: yarn install
+   # Requires lockfile to be updated first
+   # - run: yarn install --frozen-lockfile
+    - run: yarn build