Add static check for overzealous .gitignores.

.github/workflows/static_checks.yml

@@ -41,6 +41,11 @@ jobs:
           files=$(echo "$files" | grep -v 'thirdparty' | xargs -I {} sh -c 'echo "./{}"' | tr '\n' ' ')
           echo "CHANGED_FILES=$files" >> $GITHUB_ENV
 
+      # This needs to happen before Python and npm execution; it must happen before any extra files are written.
+      - name: .gitignore checks (gitignore_check.sh)
+        run: |
+          bash ./misc/scripts/gitignore_check.sh
+
       - name: File formatting checks (file_format.sh)
         run: |
           bash ./misc/scripts/file_format.sh changed.txt