Form batch builder fixes

There is still a remaining issue with this now not working with the FormAlter class. The class resolver is going to require the ::create() method, which the FormAlter class can't really use.

The form alter class implements its own createInstance so that it can always pass the $form and $form_state, with also a $context variable.

Fixes issue with parameters getting sent as a reference

This also seems to apply to 2.0.x-dev version too. Same issue there?

Automatically closed - issue fixed for 2 weeks with no activity.