[lib] Introduce getRelatedMessages to SQLiteAPI

Summary:
This diff introduces a shared interface on SQLiteAPI so the JS code in lib can hit this API on both native and web.

Depends on D12739

Test Plan:

1. In combination with later diffs, I tested a patch on both native and web that hit getRelatedMessages with a specific message ID and confirmed that it returned the message
2. I tested a message ID that did not exist and confirmed I got undefined back

Reviewers: kamil, tomek, marcin

Reviewed By: marcin

Differential Revision: https://phab.comm.dev/D12740