Use mw.hook for notifying cancel of settings window to modules

This avoids mandate of having 'cancel' method defined in settings module.
Also avoids looping of all modules while cancel is happening.

Change-Id: I87d0975f2ef1bdee61f71d66eabe3040b81876b8

resources/js/ext.uls.inputsettings.js

@@ -474,6 +474,8 @@
 						inputSettings.enableInputTools();
 					}
 				} );
+
+			mw.hook( 'mw.uls.settings.cancel' ).add( $.proxy( this.cancel, this ) );
 		},
 
 		/**