[CodeQL] Attempt to filter out scan results from 3rd party codebases

Uses [filter-sarif action](https://github.com/advanced-security/filter-sarif)

Author: sledgehammer999

.github/workflows/ci_ubuntu.yaml

@@ -144,6 +144,24 @@ jobs:
         if: startsWith(matrix.libtorrent.version, 2) && (matrix.qbt_gui == 'GUI=ON')
         with:
           category: ${{ github.base_ref || github.ref_name }}
+          output: sarif-results
+          upload: none
+
+      # Filter out results from 3rdparty codebases
+      - name: Filter CodeQL results
+        uses: advanced-security/filter-sarif@v1.1
+        if: startsWith(matrix.libtorrent.version, 2) && (matrix.qbt_gui == 'GUI=ON')
+        with:
+          patterns: |
+            -src/base/3rdparty/**
+          input: sarif-results/cpp.sarif
+          output: sarif-results/cpp.sarif
+
+      - name: Upload CodeQL SARIF
+        uses: github/codeql-action/upload-sarif@v4
+        if: startsWith(matrix.libtorrent.version, 2) && (matrix.qbt_gui == 'GUI=ON')
+        with:
+          sarif_file: sarif-results/cpp.sarif
 
       - name: Prepare build artifacts
         run: |