[lib] Implement rawMessageInfoFromClientDB for CREATE_ENTRY

Summary: Pull RawJoinThreadMessageInfo out of ClientDBMessageInfo

Test Plan: All of these implementations will be tested manually + with my prod redux store

Reviewers: ashoat, palys-swm

Reviewed By: ashoat

Subscribers: palys-swm, Adrian, karol-bisztyga, benschac, boristopalov

Differential Revision: https://phabricator.ashoat.com/D2395