We should have the following scenarios:

Unfollow 1 user, success:

- Unfollowing succeeded.
- You have successfully unfollowed ${displayName}.

Unfollow 1 user, failed:

- Unfollowing failed.
- An error occurred while unfollowing ${displayName}.

Unfollow multiple users, success:

- Unfollowing succeeded.
- You have successfully unfollowed the selected people.

Unfollow multiple users, 1 failed:

- Unfollowing failed.
- A user could not be unfollowed.

Unfollow multiple users, multiple failed:

- Unfollowing failed.
- ${errCount} users could not be unfollowed.