[lib] Introduce memberInfoSansPermissionsValidator and consume in rawThreadInfoValidator

Summary:
Introducing validator, unit tests, and consuming in rawThreadInfoValidator which fixes the validator test case which was failing.

This also expands validator so it'll support memberInfos both with and without permissions.

Depends on D12756

Test Plan: Unit tests

Reviewers: ashoat, tomek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D12758