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/resolvers/search.ex

@@ -25,4 +25,8 @@ defmodule Mobilizon.GraphQL.Resolvers.Search do
   def search_events(_parent, %{page: page, limit: limit} = args, _resolution) do
     Search.search_events(args, page, limit)
   end
+
+  def interact(_parent, %{uri: uri}, _resolution) do
+    Search.interact(uri)
+  end
 end