fix: describe() modifier calls and arch expectation methods on internal interfaces

[MrPunyapal]

Fixes two PHPStan false-positives reported against Pest's dynamic API.

describe() block modifiers (->skip(), ->with(), …)

At runtime, DescribeCall::__call() forwards every call to a fresh BeforeEachCall, which itself documents @mixin TestCall. That delegation was invisible to static analysis, so valid code like:

describe('user settings', function () {
    test('receives the dataset value', function (int $value) {
        expect($value)->toBeGreaterThan(0);
    });
})->with([10, 20]);

was reported as:

Call to an undefined method Pest\PendingCalls\DescribeCall::with().
🪪  method.notFound

Instead of hard-coding a method list into a reflection extension, a stub now declares the actual runtime relationship (@mixin BeforeEachCall) on DescribeCall, and PHPStan resolves modifiers through its native mixin logic. This means:

• skip(), with(), group(), after() and chained combinations all type-check,
• dynamically bound classes (e.g. Laravel's actingAs()) keep working through the existing TestCall extension,
• future methods added to TestCall / BeforeEachCall are picked up automatically — nothing to maintain.

Methods of @internal arch interfaces

Pest\Arch\Contracts\ArchExpectation is marked @internal upstream while being the documented public surface of architecture testing. With PHPStan's internalTag feature toggle (part of bleeding edge), documented chains such as:

arch()->expect('App\Models')
    ->toOnlyBeUsedIn('App\Repositories')
    ->ignoring('App\Models\User');

were reported as:

Call to method ignoring() of internal interface Pest\Arch\Contracts\ArchExpectation from outside its root namespace Pest.
🪪  method.internalInterface

The suppression extension already covered method.internalClass, method.internalTrait, and property.internalClass; it now also covers method.internalInterface for receivers typed as Pest\*.

Testing

• tests/Rules/DescribeCallMethodTest.php: covers ->skip(), ->with(), chained modifiers, and ->after() on describe blocks.
• tests/Rules/PestInternalClassAccessIgnoreExtensionTest.php: runs with featureToggles.internalTag: true so the regression genuinely exercises the previously failing path.

Fixes pestphp/pest#1837 and fixes pestphp/pest#1831