Add CodeQL workflow

Author: Alvaro Muñoz

.github/workflows/codeql.yml

@@ -0,0 +1,55 @@
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ 'main' ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ 'main' ]
+  schedule:
+    - cron: '49 20 * * 4'
+
+env:
+  BUILD_TYPE: RelWithDebInfo
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    container: mrts/qt-cmake-gtest-valgrind-ubuntu:v1.8
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'cpp' ]
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+      with:
+        submodules: recursive
+
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v2
+      with:
+        languages: ${{ matrix.language }}
+    
+    - name: Create build directory
+      run: mkdir build
+
+    - name: Configure CMake
+      working-directory: ${{github.workspace}}/build
+      run: cmake -DCMAKE_BUILD_TYPE=$BUILD_TYPE ..
+
+    - name: Build
+      working-directory: ${{github.workspace}}/build
+      run: cmake --build . --config $BUILD_TYPE
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v2
+      with:
+        category: "/language:${{matrix.language}}"