Completely restored authorization_code grant for user side.

Reworked oauth_sessions table.
Added extension to use MariaDB's JSON columns.
Rewritten tests for authorization_code grant for client side.
Deprecate some old shit.
[skip ci]

common/db/mysql/QueryBuilder.php

@@ -1,8 +1,10 @@
 <?php
+declare(strict_types=1);
+
 namespace common\db\mysql;
 
+use SamIT\Yii2\MariaDb\QueryBuilder as MysqlQueryBuilder;
 use yii\db\ExpressionInterface;
-use yii\db\mysql\QueryBuilder as MysqlQueryBuilder;
 
 class QueryBuilder extends MysqlQueryBuilder {