Add separate GH workflow for PRs. Add ability to run GH workflow manually

Author: andrei-punko

.github/workflows/gradle-pr.yml

@@ -0,0 +1,26 @@
+name: Pull request workflow
+on:
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+      with:   # Needed to make checkout of Git submodule too
+        submodules: 'true'
+
+    - name: Set up JDK
+      uses: actions/setup-java@v4
+      with:
+        distribution: 'temurin'
+        java-version: '21'
+        cache: 'gradle'
+
+    - name: Grant execute permission for gradlew
+      run: chmod +x gradlew
+
+    - name: Build with Gradle
+      run: ./gradlew build --no-daemon

.github/workflows/gradle.yml

@@ -2,15 +2,16 @@ name: Java CI with Gradle
 on:
   push:
     branches: [ master ]
-  pull_request:
-    branches: [ master ]
+  workflow_dispatch:
 
 jobs:
   build:
     runs-on: ubuntu-latest
 
     steps:
     - uses: actions/checkout@v4
+      with:
+        submodules: 'true'
 
     - name: Set up JDK
       uses: actions/setup-java@v4