Add the possibility to give a list of Friend to AddFriend and RemoveFriend API calls
to avoid adding them one by one.
Playfab doesn't handle all store, like Epic, Gog, Google, custom... so adding friend has to be done manually and it's really problematic, mostly because of the API call limit.
New friend list from store can be very big, and it's impossible to know if a friend have our game or not. So we have to try, adding friend, catch error and go to the next.
Xbox can handle up to 3000 friend, PSN 10000... adding one by one, with a 25 api call limit is quite hard.
