feat: allow filtering uses() by file suffix

[sunchayn]

What:

• Bug Fix
• New Feature

Description:

This PR introduces a suffix(string $suffix) method to the uses() configuration chain. This allows developers to apply different configurations to different test suites living in the same folder structure.

Example in PHPUnit,

    <testsuites>
        <testsuite name="Functional">
            <directory suffix="FunctionalTest.php">App</directory>
        </testsuite>
        <testsuite name="Unit">
            <directory suffix="UnitTest.php">App</directory>
        </testsuite>
    </testsuites>

Equivalent in Pest (as part of this PR)

Pest()
  ->uses(TestCase::class)
  ->in('App')
  ->beforeEach(...)
  ->suffix('FunctionalTest.php');

Pest()
  ->uses(\PHPUnit\Framework\TestCase)
  ->afterEach(...)
  ->in('App')
  ->suffix('UnitTest.php');

This use case is for developers willing to have a testing structure that mirrors their source code structure, so that functional and unit tests live next to each other.

└── tests/
    ├── Pest.php
    ├── TestCase.php
    └── App/
        └── Modules/
            └── Users/
                ├── ValueObjects/
                │   └── UserEmailUnitTest.php
                ├── Actions/
                │   └── LoginUserActionFunctionalTest
                └── Models/
                    ├── UserModelAnotherThingUnitTest.php
                    └── UserModelSomethingFunctionalTest.php