Route: /channels/:id/recipients/:id

[SamuelScheit]

• create a group dm/add user to group channel
• remove Recipient

[luth31]

This route supports 2 methods: PUT to create a DM group and add users to it and DELETE to remove users from it (only the owner can do it)

In order to create a DM group, 3 users are required: the one that sends the PUT request, a primary and a secondary user (their order doesn't really matter)

To create the group DM channel:
The soon-to-be owner must send a PUT request to /channels/primary_user.dm_channel.id/recipients/secondary_user.id, if succesful this will return 201 and a json object with the following structure

{
   icon: null
   id: group_dm_channel.id
   last_message_id: // id of the last message in group dm channel, usually default "Owner added User1 and User2"
   name: null
   owner_id: // user id of owner
   recipients: [ 
      PublicUser(primary_user),
      PublicUser(secondary_user),
   ]
   type: 3 (channel type for group DM)
}

To further add new users:
participant must send a PUT request to /channels/group_dm_channel.id/recipients/invited_user.id, if succesful this will return 204 and nothing else.

To remove a participant:
owner must send a DELETE request to /channels/group_dm_channel.id/recipients/removed_user.id, if succesful this will return 204 and nothing else.