feat[nonnative]: implement emulated API

[ivokub]

The circuit receives the API to perform operations. Right now, in order to implement already existing circuits/gadgets over emulated fields, we would need to rewrite the circuits to adapt the emulated arithmetic API. This is inconvenient.

Easier approach would be to implement a fake-API, which can be instantiated similarly to parameters in emulated arithmetic. Then, in native circuit it is possible to initiate the emulated API and call the Define method of an existing circuit.

(It would be even nicer if this would be integrated with #312 and the emulated API would be constructed by the compiler. But this would lead to cyclic imports. But if we would be willing to upgrade emulated arithmetic from being a gadget to a standalone package, then it could work. I think at some point we would need to do it anyways if we want to implement emulated arithmetic using custom gates.)