[lib] Update rawMessageInfoFromClientDB to handle both IMAGES and MULTIMEDIA message types

Summary:
Update rawMessageInfoFromClientDB to handle MULTIMEDIA messages in addition to IMAGES messages.

Depends on D5636

Test Plan:
Set breakpoints and observed expected behavior.

Will also be tested implicitly by subsequent diffs/video work.

Finally, will re-introduce Redux/SQLite equality checks for myself to make sure that IMAGES/MULTIMEDIA messages are persisted/unpersisted correctly.

Reviewers: tomek, marcin, ginsu, rohan, kamil, O2 Blocking Reviewers, ashoat

Reviewed By: O2 Blocking Reviewers, ashoat

Subscribers: ashoat, abosh

Differential Revision: https://phab.comm.dev/D5637