RN [fix]: updated path to hermes-inspector-msggen package from react-native/ReactCommon (#36567)

Summary:
Pull Request resolved: #36567

Changelog: [Internal]

Relative path has changed after the monorepo migration, but was overlooked

Reviewed By: cipolleschi

Differential Revision: D44290877

fbshipit-source-id: 4a5e45acf02624b11d513d56c49824a2c9ccc59e

Author: hoxyq

packages/react-native/ReactCommon/hermes/inspector/tools/run_msggen

@@ -12,7 +12,7 @@ FBSOURCE=$(hg root)
 CLANG_FORMAT="${FBSOURCE}/tools/third-party/clang-format/clang-format"
 SIGNEDSOURCE="${FBSOURCE}/tools/signedsource"
 
-pushd "../../../../packages/hermes-inspector-msggen"
+pushd "../../../../../hermes-inspector-msggen"
 
 yarn install
 yarn build