Implement Circuit Relay v2 in JS

[lidel]

go-ipfs 0.11 will ship with circuits v2, js-ipfs should be able to talk to them.

Ref. https://github.com/libp2p/specs/blob/master/relay/circuit-v2.md

[Update 2023-01-05] In-progress PR:
#1533

#1029 (comment)

[Winterhuman]

@lidel Any update on this issue?

[mpetrunic]

I would like to take this on. Should I rip circuit out of libp2p and develop it in separate repository?

[mpetrunic]

@achingbrain We agreed on a call to do it in a separate repo, but I just saw there is already https://github.com/libp2p/js-libp2p-circuit deprecated repo. Do you know why this stuff was pulled back into js-libp2p?
If we still wanna do it in a separate repo, should we unarchive this repo?

[mpetrunic]

cc @jacobheun maybe you can shed some light here.

[jacobheun]

@mpetrunic the original consolidation effort is at #384, and it links to a larger discussion in js-ipfs. The main reasoning for pulling in these core modules to js-libp2p is to reduce the overhead of having to do independent releases and rollups for modules that don't provide any value as standalone modules. I don't think it makes much sense to have libp2p-circuit externalized to js-libp2p because I don't see it being used directly elsewhere, and it's just going to add overhead to feature/release cycles. If you want to do e2e testing with libp2p, that can also create additional testing overhead.

Unless there's something specific you're trying to achieve with it being a separate module, I'd recommend keeping it here to avoid the overhead. Circuit is pretty core to libp2p, regardless of environment, whereas some of the other standalone modules are arguably environment dependent customizations.

[mpetrunic]

Honestly, my only reasoning was that we could do it in typescript and ease in migration to typescript. Will open PR with circuit v2 on libp2p repo!