Move public inputs to the front of proof

[ledwards2225]

In bberg, a Honk/PG proof explicitly contains the public inputs. They are placed at an offset from the start position (after circuit size, log circuit size, and num public inputs). For noir/ACIR, the public inputs are stripped from the proof and handled separately. This requires tracking the offset of the public inputs in a bberg proof and makes the translation from one representation to another more complicated than it needs to be. I see no reason why the public inputs cannot be placed at the start of the proof, making life easier for users of noir with the bberg backend (and simplifying logic in bberg itself).