reorganize and cleanup php server code

server/app/Support/CanImpersonateUsers.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Vanguard\Support;
+
+trait CanImpersonateUsers
+{
+    /**
+     * Check if a user can impersonate other users.
+     *
+     * @return bool
+     */
+    public function canImpersonate()
+    {
+        return $this->hasPermission('users.manage');
+    }
+
+    /**
+     * Check if a target user can be impersonated.
+     * By default, all users can be impersonated if a currently logged
+     * user is not already impersonating another user.
+     *
+     * @return bool
+     */
+    public function canBeImpersonated()
+    {
+        return ! app('impersonate')->isImpersonating();
+    }
+}