Fix private property parsing in Flow (#8340)

* Fix private property parsing in Flow

* Flow tests updated

* Fix type error

* Appropriate name was given to test folder

* Fix

* Empty

* Correct type annotation

* Add required changes in generator package

* Add required changes in flow-strip-types

scripts/tests/flow/run_babel_parser_flow_tests.js

@@ -115,6 +115,7 @@ const options = {
     "flowComments",
     "jsx",
     "objectRestSpread",
+    "classPrivateProperties",
   ],
   sourceType: "module",
   ranges: true,