[lib/native/web] factor out localID logic into helper hook

Summary:
Refactor diff to reduce tech debt when it came to building the localID for a message.

Addresses https://linear.app/comm/issue/ENG-2852/factor-out-localid-logic-into-helper-functionhook

Depends on D8711

Test Plan: flow and confirmed that there were no regressions when sending a message

Reviewers: atul, kamil

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8807