Rework contract address determination

* Do not allow override by runtime author
* Instantiate gained a new parameter "salt"

This change is done now in expecation of the upcoming code rent
which needs to change the instantiation dispatchable and
host function anyways.

The situation in where we have only something that is like CREATE2
makes it impossible for UIs to help the user to create an arbitrary
amount of instantiations from the same code.

With this change we have the same functionality as ethereum with
a CREATE and CREATE2 instantation semantic.