Contribute GH Build action to platform.ui

Adds GH verification in the hope that GH validation is faster than the
Jenkins one.

Fixes #150

.github/workflows/build.yml

@@ -0,0 +1,46 @@
+name: Build Platform UI
+concurrency: 
+    group: ${{ github.workflow }}-${{ github.ref }}
+    cancel-in-progress: true
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        fetch-depth: 0 # required for jgit timestamp provider to work
+    - uses: actions/setup-java@v2
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+        cache: maven
+    - name: Build with Maven
+      uses: GabrielBB/xvfb-action@v1
+      with:
+       run: >- 
+        mvn
+        --batch-mode
+        --global-toolchains ${{ github.workspace }}/.github/workflows/toolchains.xml
+        -Pbuild-individual-bundles
+        -Pbree-libs
+        -Papi-check
+        -Dmaven.test.failure.ignore=true
+        -Dcompare-version-with-baselines.skip=false
+        -Dproject.build.sourceEncoding=UTF-8
+        -Dorg.slf4j.simpleLogger.showDateTime=true 
+        -Dorg.slf4j.simpleLogger.dateTimeFormat=HH:mm:ss.SSS
+        -DtrimStackTrace=false
+        clean verify
+    - name: Upload Test Results
+      uses: actions/upload-artifact@v3
+      with:
+        name: test-results
+        if-no-files-found: error
+        path: '**/target/surefire-reports/*.xml'

.github/workflows/toolchains.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF8"?>
+<toolchains xmlns="http://maven.apache.org/TOOLCHAINS/1.1.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/TOOLCHAINS/1.1.0 http://maven.apache.org/xsd/toolchains-1.1.0.xsd">
+	<toolchain>
+		<type>jdk</type>
+		<provides>
+			<id>JavaSE-17</id>
+			<version>17</version>
+		</provides>
+		<configuration>
+			<jdkHome>${env.JAVA_HOME_17_X64}</jdkHome>
+		</configuration>
+	</toolchain>
+	<toolchain>
+		<type>jdk</type>
+		<provides>
+			<id>JavaSE-11</id>
+			<version>11</version>
+		</provides>
+		<configuration>
+			<jdkHome>${env.JAVA_HOME_11_X64}</jdkHome>
+		</configuration>
+	</toolchain>
+	<toolchain>
+		<type>jdk</type>
+		<provides>
+			<id>JavaSE-1.8</id>
+			<version>1.8</version>
+		</provides>
+		<configuration>
+			<jdkHome>${env.JAVA_HOME_8_X64}</jdkHome>
+		</configuration>
+	</toolchain>
+</toolchains>