[native] Refactor the members list to support any variety of role labels

Summary:
This is the same as D8067, except on native.

Depends on D8067

Test Plan:
Please see below for what the changes look like (again, for testing I allowed 'Members' to display, but only Admin/custom roles will be shown)

Reviewers: ginsu, atul

Reviewed By: atul

Subscribers: ted, ashoat, tomek

Differential Revision: https://phab.comm.dev/D8068