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>

js/src/mixins/group.ts

@@ -1,4 +1,5 @@
 import { PERSON_MEMBERSHIPS, CURRENT_ACTOR_CLIENT } from "@/graphql/actor";
+import { GROUP_MEMBERSHIP_SUBSCRIPTION_CHANGED } from "@/graphql/event";
 import { FETCH_GROUP } from "@/graphql/group";
 import RouteName from "@/router/name";
 import { Group, IActor, IGroup, IPerson, MemberRole } from "@/types/actor";
@@ -29,6 +30,17 @@ import { Component, Vue } from "vue-property-decorator";
           id: this.currentActor.id,
         };
       },
+      subscribeToMore: {
+        document: GROUP_MEMBERSHIP_SUBSCRIPTION_CHANGED,
+        variables() {
+          return {
+            actorId: this.currentActor.id,
+          };
+        },
+        skip() {
+          return !this.currentActor || !this.currentActor.id;
+        },
+      },
       skip() {
         return !this.currentActor || !this.currentActor.id;
       },