[feature/avatars] Add support for modularized avatars to ucp groups

This seems to be the last component where the new avatars system was still
missing.

PHPBB3-10018

phpBB/styles/prosilver/template/ucp_avatar_options.html

@@ -38,10 +38,12 @@
 	</div>
 <!-- END avatar_drivers -->
 	</div>
+<!-- IF not S_GROUP_MANAGE -->
 	<fieldset class="submit-buttons">
 		<input type="reset" value="{L_RESET}" name="reset" class="button2" /> &nbsp;
 		<input type="submit" name="submit" value="{L_SUBMIT}" class="button1" />
 	</fieldset>
+<!-- ENDIF -->
 	</div>
 </div>