add Qt5 compatibility wrapper for addAction and linux-qt5 CI job

.github/workflows/build.yml

@@ -173,3 +173,33 @@ jobs:
           files: Reclass-x86_64.AppImage
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  linux-qt5:
+    runs-on: ubuntu-22.04
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Install Qt5
+        uses: jurplel/install-qt-action@v4
+        with:
+          version: '5.15.2'
+          cache: true
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y ninja-build libgl1-mesa-dev
+
+      - name: Configure
+        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
+
+      - name: Build
+        run: cmake --build build
+
+      - name: Test
+        run: xvfb-run ctest --test-dir build --output-on-failure --exclude-regex "test_editor"
+        env:
+          QT_QPA_PLATFORM: offscreen