[native] Call getUserPublicKey in nativeLogInExtraInfoSelector

Summary: We make the getUserPublicKey(...) JSI call in nativeLogInExtraInfoSelector so we can include the ed25519 key in all login/registration requests from native.

Test Plan: Public key is correctly included in extraInfo

Reviewers: ashoat, tomek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D6750