[lib] Include sourceMessageID in rawThreadInfoFromThreadInfo

Summary: We don't actually use this function anywhere... but if it's in our codebase, it should work correctly, in case somebody does eventually use it for something.

Test Plan: careful inspection :)

Reviewers: palys-swm, KatPo

Reviewed By: KatPo

Subscribers: zrebcu411, Adrian, atul, subnub

Differential Revision: https://phabricator.ashoat.com/D611