find users for groups

- search for users to add to a group
- display suggested users on search results screen

TODO: actaully enable users to be added!
TODO: groups/suggested_users probably could be replaced with some logic in snippets/suggested_users.html

bookwyrm/templates/groups/find_users.html

@@ -0,0 +1,6 @@
+{% extends 'groups/group.html' %}
+
+{% block panel %}
+<h1 class="title">Add users to <a href="{{ group.local_path }}">{{ group.name }}</a></h1>
+  {% include 'groups/suggested_users.html' with suggested_users=suggested_users query=query %}
+{% endblock %}