ci: specify paths for CodeQL GH action

Author: dekobon

.github/codeql/codeql-config.yml

@@ -0,0 +1,11 @@
+name: "NGINX Wrapper CodeQL config"
+
+paths-ignore:
+  - build
+  - doc
+  - sample_configs
+paths:
+  - target
+  - app
+  - lib
+  - plugins

.github/workflows/codeql-analysis.yml

@@ -36,6 +36,7 @@ jobs:
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v1
       with:
+      config-file: ./.github/codeql/codeql-config.yml
         languages: ${{ matrix.language }}
         # If you wish to specify custom queries, you can do so here or in a config file.
         # By default, queries listed here will override any specified in a config file.