[lib] Create util function for parsing locally unique thread ID

Summary:
Created util function that is reversed version of getLocallyUniqueThreadID.
Basing on provided pending thread ID, it parses all data, that could be read from it - source message ID, thread type, and user ID list.

The goal of the function is to support navigation so that pending threads could be loaded, basing on URL (e.g. after page refresh),

Test Plan:
The function is not used yet. Tested the feature after introducing further navigation changes.
Introduced automatic tests, that could be run with cd lib && yarn test

Reviewers: tomek, atul

Reviewed By: tomek, atul

Subscribers: ashoat, adrian, abosh

Differential Revision: https://phab.comm.dev/D4446