Replace Bamboo SCDF samples build w/ GitHub actions (#159)

Add GitHub actions based CI pipeline

Resolves #155

.github/actions/build-sample-app/action.yml

@@ -0,0 +1,76 @@
+name: 'Build Sample App'
+description: 'Builds a sample app and optionally publishes to Artifactory and pushes to a Docker registry'
+inputs:
+  app-dir:
+    description: 'relative path to the app directory'
+    required: true
+  mvn-build-commands:
+    description: 'commands passed to \"mvnw" to build the app'
+    required: false
+    default: '-B clean verify'
+  artifactory-publish:
+    description: 'whether or not to publish to artifactory'
+    required: false
+    default: 'false'
+  jf-artifactory-spring:
+    description: 'encoded JFrog server id configuration'
+    required: false
+  jf-mvn-build-commands:
+    description: 'commands passed to \"jfrog rt mvn\" to publish the app'
+    required: false
+    default: '-B clean install -DskipTests'
+  docker-push:
+    description: 'whether or not to push docker image to docker hub'
+    required: false
+    default: 'false'
+  docker-registry:
+    description: 'docker registry'
+    required: false
+  docker-username:
+    description: 'docker username'
+    required: false
+  docker-password:
+    description: 'docker password'
+    required: false
+  docker-images:
+    description: 'csv of docker images to push'
+    required: false
+  docker-images-override:
+    description: 'csv of docker image tags to use when pushing (parallel array to docker-images)'
+    required: false
+runs:
+  using: "composite"
+  steps:
+    - uses: actions/checkout@v2
+
+    - uses: jvalkeal/setup-maven@v1
+      with:
+        maven-version: 3.8.4
+
+    - uses: actions/setup-java@v2
+      with:
+        distribution: adopt
+        java-version: 8
+        cache: maven
+
+    - name: Maven build
+      shell: bash
+      run: ./mvnw ${{ inputs.mvn-build-commands }}
+      working-directory: ${{ inputs.app-dir }}
+
+    - uses: ./.github/actions/build-sample-app/artifactory-publish
+      if: ${{ inputs.artifactory-publish == 'true' }}
+      with:
+        app-dir: ${{ inputs.app-dir }}
+        jf-artifactory-spring: ${{ inputs.jf-artifactory-spring }}
+        jf-mvn-build-commands: ${{ inputs.jf-mvn-build-commands }}
+
+    - uses: ./.github/actions/build-sample-app/docker-push
+      if: ${{ inputs.docker-push == 'true' }}
+      with:
+        app-dir: ${{ inputs.app-dir }}
+        docker-registry: ${{ inputs.docker-registry }}
+        docker-username: ${{ inputs.docker-username }}
+        docker-password: ${{ inputs.docker-password }}
+        docker-images: ${{ inputs.docker-images }}
+        docker-images-override: ${{ inputs.docker-images-override }}