Convert extract-tests option to an official extractor option

go/codeql-extractor.yml

@@ -19,3 +19,11 @@ file_types:
     extensions:
       - .go
 legacy_qltest_extraction: true
+options:
+  extract_tests:
+    title: Whether to include Go test files and functions in the CodeQL database.
+    description: >
+      A value indicating whether Go test files and functions should be included in the CodeQL database.
+      The default is 'false'.
+    type: string
+    pattern: "^(false|true)$"