chore: reduce redundancy with msgpack

[ludamad]

Description

Going through lists-of-fields now that we have poor-man's reflection.

This currently DOES NOT switch barretenberg to msgpack. This instead uses msgpack common reflection utils to derive such read and write functions.

For example:
MSGPACK_FIELDS(arg1, arg2);

is now used to define

void read(buf, obj) {
   read(buf, obj.arg1);
   read(buf, obj.arg2);
}

for any object that has a MSGPACK_FIELDS macro. This is also used for write

Also removes a debug utility I introduced during the hackathon that has not really been used, fine to remove

Also see AztecProtocol/barretenberg#612
There's still read and write methods that can be done similarly.

Checklist:

• [*] I have reviewed my diff in github, line by line.
• [*] Every change is related to the PR description.
• [-] I have linked this pull request to the issue(s) that it resolves.

  I should have created an issue first in hindsight, sorry

• [*] There are no unexpected formatting changes, superfluous debug logs, or commented-out code.
• [*] The branch has been merged or rebased against the head of its merge target.
• [*] I'm happy for the PR to be merged at the reviewer's next convenience.

[spalladino]

Over 550 lines deleted. Gotta love this kind of PRs!

[spalladino]

Seems like here we're reading/writing directly to a field within this struct, which is not the same as msgpack is doing I guess. Is this change ok?

[ludamad]

This was never needed I believe, see read(portal_contract_address), confusing though!

template <typename B> void read(B& it, address& addr)
{
    using serialize::read;
    fr address_field;
    read(it, address_field);
    addr = address(address_field);
}

=> 
    address(fr const& address)
        : address_(address){};

[jeanmon]

LGTM! Great to remove superfluous code.

[dbanks12]

Awesome. Lgtm