[lib] First pass at removing RawThreadInfos

Summary:
Part of https://linear.app/comm/issue/ENG-6366/rename-minimallyencodedrawthreadinfo-to-rawthreadinfo

RawThreadInfos looks like:

export type RawThreadInfos = {
  +[id: string]: LegacyRawThreadInfo | MinimallyEncodedRawThreadInfo,
};

We want to remove as many instances as possible and narrow to MinimallyEncodedRawThreadInfos. MinimallyEncodedRawThreadInfos will eventually be renamed to RawThreadInfos

Depends on D10626

Test Plan: flow

Reviewers: ashoat, ginsu, tomek

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D10627