[lib] Handle new id schema in thread regexes

Summary:
ENG-4586

Updates threadRegex in url-utils.js and pendingThreadIDRegex to handle both old and new id schemas.

Test Plan:

• checked if navigating back and forth works on web and on desktop
• searched for regex in our codebase and checked if there are any more instances that need to be updated
• yarn test

Reviewers: tomek, ginsu, rohan

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D8744