Add for method to factory

[joshhanley]

This PR allows you to pass the state id through a for() method instead of needing to pass it as a second parameter into the create method.

MyState::factory()->for($myStateId)->create([...]);

The old way will still work

MyState::factory()->create([...], $myStateId);

If for some reason, someone uses both, the ID passed into the create method will take preference.

MyState::factory()->for($myStateId1)->create([...], $myStateId2); // This will have a state ID of 2