[lib] Add MemberInfoSansPermissions support to threadOtherMembers

Summary:
This resolves a flow issue when RawThreadInfo.members are of type MemberInfoSansPermissions.

Depends on D12315

Test Plan: NA, flow issue later in stack is resolved.

Reviewers: ashoat, ginsu, tomek

Reviewed By: ginsu

Differential Revision: https://phab.comm.dev/D12321