feat(acp): autocomplete user search for welcome notifications

public/src/admin/settings/notifications.js

@@ -0,0 +1,18 @@
+'use strict';
+
+define('admin/settings/notifications', [
+	'autocomplete',
+], function (autocomplete) {
+	var	Notifications = {};
+
+	Notifications.init = function () {
+		var searchInput = $('[data-field="welcomeUid"]');
+		autocomplete.user(searchInput, function (event, selected) {
+			setTimeout(function () {
+				searchInput.val(selected.item.user.uid);
+			});
+		});
+	};
+
+	return Notifications;
+});