* FEATURE: upload an avatar option for uploading avatars with selectable avatars
Allow staff or users at or above a trust level to upload avatars even when the site
has selectable avatars enabled.
Everyone can still pick from the list of avatars. The option to upload is shown
below the selectable avatar list.
refactored boolean site setting into an enum with the following values:
disabled: No selectable avatars enabled (default)
everyone: Show selectable avatars, and allow everyone to upload custom avatars
tl1: Show selectable avatars, but require tl1+ and staff to upload custom avatars
tl2: Show selectable avatars, but require tl2+ and staff to upload custom avatars
tl3: Show selectable avatars, but require tl3+ and staff to upload custom avatars
tl4: Show selectable avatars, but require tl4 and staff to upload custom avatars
staff: Show selectable avatars, but only allow staff to upload custom avatars
no_one: Show selectable avatars. No users can upload custom avatars
Co-authored-by: Régis Hanol <regis@hanol.fr>
Jeff Wong