github/actions: merge CodeQL workflow into lone's

It's easier to deal with when everything is in the same file.
Also take this opportunity to update all CodeQL actions to v3.

.github/workflows/lone.yml

@@ -66,3 +66,32 @@ jobs:
 
     - name: Test lone
       run: make test
+
+  analyze:
+    name: CodeQL analysis
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'cpp' ]
+
+    steps:
+    - name: Checkout lone repository
+      uses: actions/checkout@v4
+
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v3
+      with:
+        languages: ${{ matrix.language }}
+
+    - name: Build lone
+      run: make
+
+    - name: Perform CodeQL analysis
+      uses: github/codeql-action/analyze@v3
+      with:
+        category: "/language:${{matrix.language}}"