Remove interior mutability hack for chip record generators

[iammadab]

After #80 each record-generating chip holds its underlying memory-checking structure in the following way:

pub struct Chip<Ext: ExtensionField> {
    rom_handler: Rc<RefCell<ROMHandler<Ext>>>,
}

The current architecture has a common memory-checking structure from which all chips must read and write.

Rather than having global memory-checking structures for all chips, a better approach will be to have separate memory-checking structures for each chip i.e. on chip instantiation, each chip will create its record-tracker.

After an instruction has finalized all its chip operations, we can combine the records into singular RAM and ROM records.

This removes the interior mutability hack while preserving the chip-first approach.

[hero78119]

Hi, this type definition well address the problem, however I feel like a slightly over-design. I proposed another alternative, aiming for mutability happened in just one place under a struct :)

Besides, to simplify, how about we unify OAMHandler & RamHandler into OAMHandler, and define ram_read/ram_write/ram_read_mixed,ram_write_mixed 4 new function in OAMHandler to aborb RamHandler logic in one place

define new ChipHandler to encaptulate all XXXhandlers internally. So the mutability borrow wont spread everywhere

let mut chip_handler = ChipHandler::new(&mut circuit_builder, challenges);

fn new(challenge) -> Self {
    ...
    ChipHandler {
         rom_handler: ROMHandler::new(challenges.clone))
         oam_handler: OAMHandler::new(challenges))
    }
}

chip operation: take lookup_handler + circuit_builder

For example

RangeChip::range_check_stack_top(&mut lookup_handler, &mut circuit_builder, stack_top_l);

finalize in one call on chip_handler

let (ram_load_id, ram_store_id
, rom_id) = chip_handler.finalize(&mut circuit_builder)

[iammadab]

closed by #94