[native] Navigate to invite links instead of add members modal

Summary:
issue: ENG-7793
We don't want users to be able to add users to community roots - invite links should be used instead.

Test Plan:
[for non-community-root] Tested that for chats the "Add members" button still navigates to "Add members" modal.
[for community root] Tested that if invite link exists, "Add members" button navigates to "Invite link" modal.
[for community root] Tested that if invite link doesn't exist, but user has permissions to create one, "Add members" button navigates to "Manage invite links" modal.
[for community root] Tested that if invite link doesn't exist and the user doesn't have premissions to creat it, the button is disabled.

Reviewers: tomek, kamil

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12284