Allow to join an open group

Also:

* Refactor interacting with a remote event so that you can interact with
  a remote group as well
* Add a setting for group admins to pick between an open and invite-only
  group
* Fix new groups without posts/todos/resources/events/conversations URL
  set
* Repair local groups that haven't got their
  posts/todos/resources/events/conversations URL set
* Add a scheduled job to refresh remote groups every hour
* Add a user setting to pick when to receive notifications when there's
  new members to approve (will be used when this feature is available)
* Fix pagination for members

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/graphql/schema/actors/group.ex

@@ -17,7 +17,7 @@ defmodule Mobilizon.GraphQL.Schema.Actors.GroupType do
   Represents a group of actors
   """
   object :group do
-    interfaces([:actor])
+    interfaces([:actor, :interactable])
 
     field(:id, :id, description: "Internal ID for this group")
     field(:url, :string, description: "The ActivityPub actor's URL")
@@ -196,6 +196,10 @@ defmodule Mobilizon.GraphQL.Schema.Actors.GroupType do
 
       arg(:visibility, :group_visibility, description: "The visibility for the group")
 
+      arg(:openness, :openness,
+        description: "Whether the group can be join freely, with approval or is invite-only."
+      )
+
       arg(:avatar, :picture_input,
         description:
           "The avatar for the group, either as an object or directly the ID of an existing Picture"