Controlled accounts

Is your feature request related to a problem? Please describe.
Companies, schools and parents would like ability to white- and black- list certain users to certain guilds,
channels and user groups. Bridge bots could also make use of this feature.

Describe the solution you'd like

• Group whitelist/blacklist create (list of guilds and DM targets)
• Group whitelist/blacklist fetch
• Group whitelist/blacklist delete
• Discriminator range reserve
• Discriminator range unreserve
• Create controlled account (#408)
• Delete controlled account (#351)
• Fetch all accounts controlled by self
• Apply group white/blacklist to controlled user
• Action in behalf of controlled user

Detailed description of the endpoints

Create controlled account: This endpoint shall create a controlled user account.
Parameters:

• username: Name of the controlled account
• tag: Discriminator of the controlled account
• scope: Array of group white/blacklists to apply (if both white- and blacklists are present, then blacklist is subtracted from the whitelist)
• controller: The user who controls the account (implicit in writes, returned in reads of the controlled user)
• rights: Initial rights of the user
  Returns: If unauthorised to create a controlled user or apply one or more of the control flags, return 403 Forbidden.
  On success, return 200 OK.

Delete controlled account: This endpoint shall remove a controlled user account.

Parameters: same as /users/@me/delete, but controlled accounts cannot initiate account delete on their own.
Returns: If unauthorised to delete the user or apply one or more of the control flags, return 403 Forbidden. On attempt to delete a non-existent user in a discriminator range controlled by said user, return 400 Bad Request.
On success, return 200 OK.

Group white- and blacklist objects:
Parameters:

• whitelist: if true, a whitelist, else, a blacklist
• guilds: list of guilds
• users: list of DM targets
• roles: list of roles
  If unauthorised to create a controlled user or apply one or more of the control flags, return 403 Forbidden.
  On success, return 200 OK.

Group whitelist/blacklist create:

• users: Array of user IDs to be affected initially
• scope Group whitelist/blacklist object

If unauthorised to create a controlled user or apply one or more of the control flags, return 403 Forbidden.
On success, return 200 OK.

Discriminator range reserve: Reserve certain discriminators for a certain account controller. An account controller can only reserve discriminators for itself, not for other controllers.
Parameters:

• include: a pair of discriminators, which denote an inclusive range
• exclude: array of pairs of discriminators, which denote ranges to be excluded from above

If unauthorised to create a controlled user or apply one or more of the control flags, return 403 Forbidden.
On success, return 200 OK.

Discriminator range fetch: Returns the reservation by reservation ID. Discriminator range reservations shall be returnable by any user.

If unauthorised to create the reservation or attempts to re-reserve an already reserved range, return 403 Forbidden.
On success, return 200 OK.

Discriminator range delete: Deletes the reservation by reservation ID. Only the user that created the reservation can delete it.

If unauthorised to unreserve the range, return 403 Forbidden. On attempt to delete a non-existent reservation, return 400 Bad Request.
On success, return 200 OK.

Apply group white/blacklist to controlled user: Applies group scope limits to a given user.
Parameters:

• user: User ID to apply the group white/blacklist.
• scope Array of IDs of group white/blacklist to be applied. A user can have as many scopes applied as wanted.

Sub-tasks

• Account controller configuration
• Create/delete controlled account
• Controlled account configuration
• Act on behalf of a controlled account
• Controlled account limits&exemptions