Skip entity auto-detection when explicitely passed

The call to .first might cause an unnecessary db call

    present SomeModel.active, with: Entities::SomeModel

__generated sql calls

    Somemodel Load (1.0ms)  SELECT [...] ORDER BY id LIMIT 1
    Somemodel Load (0.4ms)  SELECT [...] ORDER BY id

The first call is to determine the entity, which in this case is not necessary since it has been passed to `present`