Client: Guilds Discovery (#8529)

* wip: add guilds discovery page

* add public guilds page

* fix and add tests for the groups utilities mixin

website/client/mixins/groupsUtilities.js

@@ -0,0 +1,25 @@
+// TODO if we only have a single method here, move it to an utility
+// a full mixin is not needed
+
+import { TAVERN_ID } from '../../common/script/constants';
+
+export default {
+  methods: {
+    isMemberOfGroup (user, group) {
+      if (group._id === TAVERN_ID) return true;
+
+      // If the group is a guild, just check for an intersection with the
+      // current user's guilds, rather than checking the members of the group.
+      if (group.type === 'guild') {
+        return user.guilds.indexOf(group._id) !== -1;
+      }
+
+      // Similarly, if we're dealing with the user's current party, return true.
+      if (group.type === 'party') {
+        return user.party._id === group._id;
+      }
+
+      return false;
+    },
+  },
+};