message: Update CODEOWNERS for appui-test-app
diff: @@ -158,6 +158,8 @@ rush.json @iTwin/itwinjs-core-admins
  /test-apps/synchro-schedule-importer @iTwin/itwinjs-core-display
  /test-apps/ui-test-app @iTwin/itwinjs-core-ui
  /test-apps/ui-items-providers-test @iTwin/itwinjs-core-ui
  +/test-apps/appui-test-app @iTwin/itwinjs-core-ui
  +
  /tools/backend-webpack @calebmshafer @wgoehrig
  /tools/build @calebmshafer @wgoehrig
  