[lib] Move messageTypes enum to a separate file

Summary: No logic changes. This is done to avoid ayclic imports between message-types and files in types/messages after adding the validators

Test Plan: Run app on web and ios, check if they throw any unexpected errors.

Reviewers: kamil, inka, tomek

Reviewed By: tomek

Subscribers: ashoat, atul

Differential Revision: https://phab.comm.dev/D7564