Allow logged account to add other users as friends

Housekeeping job for pending requests.
Requested by [chaZmich](https://github.com/chaZmich) on Jan 19th, 2022, [here](https://github.com/achievements-app/psn-api/issues/34#issuecomment-1016463510).

Reason: Allows tracking for players that don't have their trophies set to public, without making them do so.

Reference: [Send Friend Request](https://github.com/cubehouse/PSNjs#sendfriendrequestusername-message-callback), [Accept Friend Request](https://github.com/cubehouse/PSNjs#addfriendusername-callback).

We already have a method to retrieve the friends list, so it's probably good to use that before trying to add/accept friend requests.