Store hermes stable artifacts inside Pods directory (#40733)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/40733

Node package managers may purge or recreate `node_modules/react-native` when adding/removenf project dependencies. Storing hermes iOS artifacts inside `node_modules/react-native/sdks` is not reliable.
This diff moves those artifacts to `Pods/hermes-engine-artifacts`.
Should fix https://github.com/facebook/react-native/issues/39903
Changelog: [Internal]

Reviewed By: cipolleschi

Differential Revision: D50081559

fbshipit-source-id: a130898e12fb6275cadaef7617bf4b6a09e6487e