GH-1 - Initial port of Moduliths project.

Basically the state of commit c7cf939 of https://github.com/moduliths/moduliths for further development under the Spring umbrella.

.github/workflows/build.yaml

@@ -0,0 +1,49 @@
+name: Maven Build
+
+on:
+  push:
+    branches: [ main, 1.3.x ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    name: Build project
+    runs-on: ubuntu-latest
+
+    steps:
+
+    - name: Check out sources
+      uses: actions/checkout@v2
+
+    - name: Set up JDK 17
+      uses: actions/setup-java@v2
+      with:
+        distribution: 'temurin'
+        java-version: 17
+        cache: 'maven'
+
+    - name: Build with Maven
+      run: ./mvnw -B
+
+  integrations:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        boot-version: ["2.5.14", "2.6.9", "3.0.0-SNAPSHOT"]
+    name: Integration test (Boot ${{ matrix.boot-version }})
+    needs: build
+    steps:
+
+    - name: Check out sources
+      uses: actions/checkout@v2
+
+    - name: Set up JDK 17
+      uses: actions/setup-java@v2
+      with:
+        distribution: 'temurin'
+        java-version: 17
+        cache: 'maven'
+
+    - name: Build with Maven (Boot ${{ matrix.boot-version }})
+      run: sed -i -e 's/2.7.1/${{ matrix.boot-version }}/g' ./pom.xml && ./mvnw dependency:list -B && ./mvnw -B