poc: add rebuild script to ci to re-produce failue build

Author: miettal

.github/workflows/build.yml

@@ -1,5 +1,6 @@
 name: Build OpenEMS
 on:
+  push:
   pull_request:
     types: [opened, synchronize, reopened]
 
@@ -21,6 +22,12 @@ jobs:
       - name: Build all Java packages
         run: ./gradlew build
 
+      - name: Clean all Java packages
+        run: ./gradlew clean
+
+      - name: Re-Build all Java packages
+        run: ./gradlew build
+
       - name: Resolve OpenEMS bundles
         run: ./gradlew resolve
 
@@ -94,4 +101,4 @@ jobs:
           node_modules/.bin/ng build -c "openems,openems-edge-prod,prod"
           node_modules/.bin/ng lint
           export CHROME_BIN=/usr/bin/google-chrome-stable
-          npm run test -- --no-watch --no-progress --browsers=ChromeHeadlessCI
+          npm run test -- --no-watch --no-progress --browsers=ChromeHeadlessCI