[admin] add username change log

resources/lang/zh_CN/username-change-log.php

@@ -0,0 +1,13 @@
+<?php
+
+return [
+    'change_type' => [
+        \App\Models\UsernameChangeLog::CHANGE_TYPE_USER => '用户',
+        \App\Models\UsernameChangeLog::CHANGE_TYPE_ADMIN => '管理员',
+    ],
+    'labels' => [
+        'username_old' => '旧用户名',
+        'username_new' => '新用户名',
+        'change_type' => '修改类型',
+    ],
+];