[web] Show option to change role from the members modal
Summary:
As a first step in allowing admins to change member roles, the member panel option needed to be refactored to a more general approach to 'Change Role', as opposed to just toggling an admin status.
https://linear.app/comm/issue/ENG-4037/show-option-to-change-role-from-the-members-modal
Test Plan:
Confirm that the dropdown shows the updated icon and text
Reviewers: atul, ginsu
Reviewed By: atul
Subscribers: ted, ashoat, tomek
Differential Revision: https://phab.comm.dev/D8135