[lib] Introduce rawThreadInfoValidator and consume in threads-state-sync-spec

Summary:
Introduce validator that can handle both LegacyRawThreadInfo and MinimallyEncodedRawThreadInfo because keyserver will be handling both.

Updated validator was required to update threads-state-sync-spec which will allow us to update rest of thread update/thread "ops" code.

Depends on D10210

Test Plan: Flow/CI/validator will fail during testing if not defined correctly.

Reviewers: ashoat, ginsu, tomek, rohan

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D10211