Attributes improvements

[DavertMik]

• Added Prepare attribute
• Added support for repeatable attributes (Group, Env)
• Updated tests

// define groups in 1 attribute
#[Group('g1', 'g2')]

// or in multiple
#[Group('g1')]
#[Group('g2')]

• Added support for Given/When/Then attributes (repeatable) for BDD:

<?php
namespace Tests\Support;

use Codeception\Attribute\Given;
use Codeception\Attribute\When;
use Codeception\Attribute\Then;

class AcceptanceTester extends \Codeception\Actor
{
    use _generated\AcceptanceTesterActions;

     #[Given('I have product with :num1 price in my cart')]
     public function iHaveProductWithPriceInMyCart($num1)
     {
        throw new \PHPUnit\Framework\IncompleteTestError("Step `I have product with :num1 price in my cart` is not defined");
     }

     #[When('I go to checkout process')]
     public function iGoToCheckoutProcess()
     {
        throw new \PHPUnit\Framework\IncompleteTestError("Step `I go to checkout process` is not defined");
     }

Corresponding changes were reflected in documentation):

Codeception/codeception.github.com#611