- implement the IVC `FoldingScheme` trait for HyperNova
- refactor Nova's preprocess logic to make it simplier to use
- add to Decider trait (& Nova's DeciderEth) a preprocess method
- get rid of the `init_nova_ivc_params` and `init_ivc_and_decider_params` methods in `examples` since this is achieved with the `FS::preprocess` & `Decider::preprocess` methods
  - (update the examples code to the simplified interface using
    FS::preprocess & Decider::preprocess)

* Add BN254 and Grumpkin Poseidon configurations

* Remove unncecessary comment

* Fix BN254 Poseidon config test

* Correction

* Update folding-schemes/src/transcript/poseidon/grumpkin.rs

Co-authored-by: Pierre <pdaixmoreux@gmail.com>

---------

Co-authored-by: Pierre <pdaixmoreux@gmail.com>

* circom: add external_inputs

* adapt new external_inputs interface to the FoldingScheme trait and Nova impl

* adapt examples to new FCircuit external_inputs interface

* add state_len & external_inputs_len params to CircomFCircuit

* add examples/circom_full_flow.rs

* merge the params initializer functions, clippy

* circom: move r1cs reading to FCircuit::new instead of each step

* CI/examples: add circom so it can run the circom_full_flow example

* expose params & structs for external usage

* add full_flow example, move examples into 'examples' dir

* Add external inputs logic to F function/circuit. Add an example of usage with external inputs too.

* Add examples run into CI