Admin scopes BE handling

Origins: pleroma-fe!1032 (merged), pleroma-fe!1034 (merged)

Questions to discuss:

1. Once PleromaFE develop branch receives support of admin scope (pleroma-fe!1034 (merged)), what do we do with previously issued PleromaFE apps / authorizations / tokens?

• add admin scope to PleromaFE app records?
• delete PleromaFE authorizations / tokens belonging to users with is_admin flag (so users need to sign in again) or append admin scope to them?

2. What do we do once user is promoted to admins / downgraded from an admin to a regular user?

• sign user out from all applications?
• other

3. Only allow admins to obtain admin scope?

• assumed yes, but there is an alternative suggestion: pleroma-fe!1034 (comment 48315)