PS: support buildmode none in extractor

Author: LWSimpkins

powershell/codeql-extractor.yml

@@ -3,6 +3,8 @@ display_name: "powershell"
 version: 0.0.1
 column_kind: "utf16"
 legacy_qltest_extraction: true
+build_modes:
+  - none
 file_types:
   - name: powershell
     display_name: powershellscripts