Fix issue with toArray

[WendellAdriel]

This fixes the issue described in #78
When using toArray (or any other method to transform the DTO into another structure), there was an inconsistency with the data from the DTO property and the resulting structure.

This PR introduces a fix and a test case to cover the scenario.

[xHeaven]

Hey @WendellAdriel!

We just realized at the team that this fix broke something else.

Lets pretend we have this DTO:

class TestDTO extends SimpleDTO
{
    #[Map(data: 'data')]
    public array $foobar;

    protected function defaults(): array
    {
        return [];
    }

    protected function casts(): array
    {
        return [];
    }
}

Lets use this DTO like this:

TestDTO::fromArray(['data' => ['12345']]);

In 3.6.0, this code outputs this:

App\TestDTO {
    +foobar: [
      "12345",
    ],
}

However, after 3.6.1, the output is this:

App\TestDTO {
    +foobar: [],
}

This is a quite breaking change, as we can't really tell random API providers to not provide a key called data. We also wouldn't like to manually map the data key into something else, I mean that's the entire point of having a DTO that does this for us in the first place.

Can we get this fixed, or is there a workaround that doesn't involve manual mapping?

Thanks!