Feature: Add selection form profile avatar from certain list

[ReDBrother]

Battle.net have custom list of avatar which users can choose

Backend: Add new prop "current_profile_avatar_url" for user model and api for update and retrieve list of available avatars and their avatars from discord/github if they link external profiles

Frontend: Add new internal page for user profile with list of available avatars. Especially show github/discord avatars if needs And highlights chosen avatar on list.

Page Schema:

Show avatar on other pages (game preview, custom tournaments) by "current_profile_avatar_url" or according to the logic already written (it will be a default)