Bug: Prevents the use of global functions with parameters [Validation]

[demortx]

Direction
Prevents the use of custom global functions
Exemple:
function max_int($int, $val, $data = null) { if ($val > $int) return false; else return true; }

$rules['sum'] = array( 'label' => lang('Api/v1/Globals/Payment.sum'), 'rules' => 'min_int[5]', 'errors' => [ 'min_int' => 'min_int...', ] );

Describe the bug
A clear and concise description of what the bug is.

CodeIgniter 4 version
4.0.0-rc.3

Affected module(s)
Validation

Expected behavior, and steps to reproduce if appropriate
CRITICAL - 2019-10-21 19:01:27 --> min_int is not a valid rule. #0 /var/www/site.ru/system/Validation/Validation.php(294): CodeIgniter\Validation\Exceptions\ValidationException::forRuleNotFound('min_int') #1 /var/www/site.ru/system/Validation/Validation.php(175): CodeIgniter\Validation\Validation->processRules('sum', '\xD0\xA1\xD1\x83\', '50', Array, Array) #2 /var/www/site.ru/app/API/v1/Globals/Payment.php(123): CodeIgniter\Validation\Validation->run(Array) #3 /var/www/site.ru/system/CodeIgniter.php(847): App\API\v1\Globals\Payment->checkout() #4 /var/www/site.ru/system/CodeIgniter.php(338): CodeIgniter\CodeIgniter->runController(Object(App\API\v1\Globals\Payment)) #5 /var/www/site.ru/system/CodeIgniter.php(246): CodeIgniter\CodeIgniter->handleRequest(NULL, Object(Config\Cache), false) #6 /var/www/site.ru/public_html/index.php(45): CodeIgniter\CodeIgniter->run() #7 {main}

Context

• OS: [Linux]
• Web server [apache2handler]
• PHP version [7.2.19-1+ubuntu16.04.1+deb.sury.org+1]

[lonnieezell]

This is not a bug. CI4 uses a different way of getting custom validation rules than previous versions. Please see the validation docs.