fix: filters passed to the $routes->group() are not merged into the filters passed to the inner routes

[kenjis]

Description
Fixes #9063

$routes->group('', ['filter' => ['csrf']], static function ($routes) {
    $routes->get('getuserinfo', 'Mmeber::getUserInfo', ['filter' => ['honeypot']]);
});

Before:

+--------+-------------+------+--------------------------------------+----------------+---------------+
| Method | Route       | Name | Handler                              | Before Filters | After Filters |
+--------+-------------+------+--------------------------------------+----------------+---------------+
| GET    | getuserinfo | »    | \App\Controllers\Mmeber::getUserInfo | honeypot       | honeypot      |
+--------+-------------+------+--------------------------------------+----------------+---------------+

After:

+--------+-------------+------+--------------------------------------+----------------+---------------+
| Method | Route       | Name | Handler                              | Before Filters | After Filters |
+--------+-------------+------+--------------------------------------+----------------+---------------+
| GET    | getuserinfo | »    | \App\Controllers\Mmeber::getUserInfo | csrf honeypot  | honeypot csrf |
+--------+-------------+------+--------------------------------------+----------------+---------------+

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide