[6.x] Allow passing an array to resource::collection()

[SjorsO]

This PR is similar to #25213. I'm trying to use a resource for an array of "normal" classes/objects:

public function index()
{
    /** @var SomeClass[] $array */
    $array = $this->getClasses();

    return SomeResource::collection($array);
}

This currently doesn't work, and throws the following exception: Call to a member function first() on array at /Illuminate/Http/Resources/CollectsResources.php:24.

For now, I'm wrapping the array in a collection, and then passing it to the resource:

return SomeResource::collection(collect($array));

With this PR, I can just pass the array directly.