public-vm(aztec-nr): macro flag for transpilation

[Maddiaa0]

Overview

With / assuming the completion of #4227

The avm bytecode is generated by running ./transpile <input> <output> for each noir output artifact.

If we were to ship this approach to developers once the AVM becomes inshrined within the protocol, we would be required to also ship a complication aztec-nargo build script that ran the transpiler aswell.

I do not think we want to do this, but instead we should have something that is integrated with noir's current aztec-macros abstraction leak.

#[aztec(public-vm)]
fn transfer_public(to: Field, amount: Field) {
...
}

Where does the code go?

Aztec noir's macros currently only perform preprocessing, but to perform transpilation from within aztec-nargo we want to perform postprocessing.

Implementation Steps

Tasks

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1. feat(noir): add temporary noir macro for AVM functions #4269
   C-avm +1
   
2. Create the #[aztec(public-vm)] attribute tag that does not include the all of the public kernel preamble. ( i think this is the right approach )
3. Create a postprocesing step within aztec-nargo ( transform the json output - this should not be too intrusive )
4. long term: enshirne the generation of avm bytecode from aztec-nargo ( without transpilation )
5. remove #[aztec(public-vm)] attribute, as it will be merged with #[aztec-public]

[fcarreiro]

This was completed by @dbanks12 . Long-term enshrining has to be debated :)