Add include traversing methods to ApiResource

[AndreyTheK]

Sample usage:

class UserController extends ApiController
{

    protected function getBuilder()
    {
        return QueryBuilder::for(User::class)
            ->allowedIncludes([
                ApiIncludes::dummy('foo'),
            ])
        ;
    }
}


class UserResource extends ApiResource
{
    public function toArray($request)
    {
        return [
            'userid' => $this->userid,
            'bar'    => $this->whenIncluded('foo', fn() => 'baz!')
        ];
    }
}

GET /v3/api/users?include=foo

{"data":[{"userid":1149920,"bar":"baz!"},{"userid":1149921,"bar":"baz!"},{"userid":1149922,"bar":"baz!"}, ...