[lib] Update memberHasAdminPowers to handle MinimallyEncodedMemberInfo

Summary: Update memberHasAdminPowers to use hasPermission utility when dealing with MinimallyEncodedMemberInfo.

Test Plan: Flow, will add unit tests later on

Reviewers: ashoat, ginsu, tomek, rohan

Reviewed By: ashoat

Subscribers: wyilio

Differential Revision: https://phab.comm.dev/D9839