[lib] Create a thin thread when some users don't support thick threads

Summary:
Check if all the users support thick threads and chose thread type accordingly.

https://linear.app/comm/issue/ENG-9257/limit-chat-candidates-to-users-who-are-registered-with-identity

Test Plan: On both native and web checked if the correct thread type is created, when sending text message, depending on the presence of members in AuxUserStore

Reviewers: kamil, will

Reviewed By: kamil

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D13404