[lib] Add runtime check to minimallyEncodeThreadCurrentUserInfo ensure argument isn't already minimally encoded

Summary:
Ran into issue described here: https://phab.comm.dev/D10314#298619 where I was accidentally passing MinimallyEncodedThreadCurrentUserInfo to minimallyEncodeThreadCurrentUserInfo. Obviously this shouldn't have happened and the type system would have prevented it, but because I didn't validate and ascertain type of ClientDBThreadInfo (which is effectively any typed since it's being JSON.parsed from stringified JSON stored in SQLite) before passing to minimallyEncodeThreadCurrentUserInfo, it "re-minimally encoded it" silently and replaced permissions: "3" with permissions: "0" which led to eg ThreadList showing no entries and also no errors.

Again, updating convertClientDBThreadInfoToRawThreadInfo to properly validate all data that comes from the clientDB should prevent this invariant from being necessary, but I don't think it hurts to add runtime checks for now so any similar issues become immediately clear. Will also add these checks to all the other minimallyEncode* functions, though will pass on adding unit tests for now. Will also make sure to add tests to convertClientDBThreadInfoToRawThreadInfo to make sure it correctly handles ClientDBThreadInfo created from LegacyRawThreadInfos, MinimallyEncodedRawThreadInfos, and generally malformed ones.

Also added unit test that would've previously failed silently leading to incorrect permissions being stored in Redux to ensure that it now throws.

Depends on D10314

Test Plan: Unit tests, issue observed in D10314 is no longer occurring.

Reviewers: ashoat, ginsu, tomek, rohan

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D10325