[lib] Replace threadMemberHasPermission logic in appendUserInfo

Summary:
Instead of checking KNOW_OF using threadMemberHasPermission which requires member.permissions for all members, we use the member's role permissions to determine if they have KNOW_OF.

This was the one usage of threadMemberHasPermission, so now it can be fully removed as well.

Depends on D12158

Test Plan:
Added log statements at each step and ensured that values were as expected:

Reviewers: ashoat, tomek, varun, ginsu

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D12259