* Implement Nova IVC's new & prove_step methods

Implement Nova IVC's new & prove_step methods (without CycleFold part yet)

* transcript.absorb_point err handling, and update C.xy() usage

* add transcript usage to IVC prove, add NovaTranscript trait extending Transcript trait, refactor NIFS.P to allow absorbing in transcript inbetween

* Implement Nova's IVC.V method (without CycleFold part yet)

* clippy lints

* move challenge r computation in-circuit

* reuse computed points with coordinates over CF (non-native) to save constraints in AugmentedFCircuit

(constraint count went down ~6k)

* rm 128 bit constant

* add params to Errors

* Updates from review suggestions. Additionally refactored nova/nifs fold, and rm transcript from nova/IVC.

- Updates from PR suggestions
- Additionally updated:
  - in nova/nifs.rs: reuse folded_committed_instance for verify_folded_instance, computationally is the same, but reusing the same code so avoiding duplication and having an error on one of the two versions.
  - in nova/ivc.rs: remove transcript from IVC (not needed, it uses the RO)