Add a workflow to prepare the next release cycle

This workflow is triggered by the milestone creation and automatically
performs the updates of the master pom and target to be prepared for
usage in the submodules and creates a PR. This PR will then trigger the
deploy of the changed xmls, so it can be used immediatly to adjust the
sub-projects.

.github/workflows/prepareRelease.yml

@@ -0,0 +1,43 @@
+name: Prepare Next Release
+on:
+  milestone:
+    types: [created]
+
+jobs:
+  prepare:
+    runs-on: ubuntu-latest
+    if: contains(github.event.milestone.description, 'Release')
+    permissions:
+      pull-requests: write
+      contents: write
+    steps:
+    - id: get-release-name
+      run: |
+        name=$(echo ${{ github.event.milestone.due_on }} | cut -d- -f-2)
+        echo "name=$name" >> $GITHUB_OUTPUT
+    - uses: actions/checkout@v3
+      with:
+        ref: master
+    - name: Set up JDK
+      uses: actions/setup-java@v3
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+        cache: maven
+    - name: Update Main Versions
+      run: mvn -U -ntp -f eclipse-platform-parent org.eclipse.tycho:tycho-versions-plugin:4.0.0-SNAPSHOT:set-version -DnewVersion=${{ github.event.milestone.title }}.0-SNAPSHOT -Dmodules=../eclipse.platform.releng.prereqs.sdk
+    - name: Update Release Versions
+      run: mvn -ntp -f eclipse-platform-parent/pom.xml --non-recursive org.eclipse.tycho:tycho-versions-plugin:4.0.0-SNAPSHOT:set-property -Dproperties=releaseNumberSDK,releaseNumberPlatform,releaseName -DnewReleaseName=${{ steps.get-release-name.outputs.name }} -DnewReleaseNumberSDK=${{ github.event.milestone.title }} -DnewReleaseNumberPlatform=${{ github.event.milestone.title }}
+    - name: Create Pull Request for Release ${{ github.event.milestone.title }}
+      uses: peter-evans/create-pull-request@v4
+      with:
+        commit-message: Prepare Release ${{ github.event.milestone.title }}
+        branch: prepare_R${{ github.event.milestone.title }}
+        title: Prepare Release ${{ github.event.milestone.title }}
+        body: A new Release Milstone was created, please review the changes and merge if appropriate.
+        delete-branch: true
+        milestone: ${{ github.event.milestone.number }}
+        add-paths: |
+            eclipse-platform-parent/pom.xml
+            eclipse.platform.releng.prereqs.sdk/pom.xml
+