[gh-actions] Add codeql config file to exclude compiled js, html, css

.github/codeql/codeql-config.yml

@@ -0,0 +1,4 @@
+name: "forked-daapd CodeQL config"
+
+paths-ignore: 
+  - htdocs

.github/workflows/codeql-analysis.yml

@@ -30,6 +30,8 @@ jobs:
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v1
+      with:
+        config-file: ./.github/codeql/codeql-config.yml
       # Override language selection by uncommenting this and choosing your languages
       # with:
       #   languages: go, javascript, csharp, python, cpp, java