Migrate go-libp2p-daemon into mono-repo

[MarcoPolo]

This thing is destined to be out of date as long as it lives outside this repo. I think we should be able to get rid of it completely at some point with test-plans, but until we have that replacement we should support it since it is important for js-libp2p tests.

Originally posted by @MarcoPolo in libp2p/go-libp2p-daemon#273 (comment)

[lidel]

We have two "libp2p daemons":

• https://github.com/libp2p/go-libp2p-daemon/ - created as a light binary that can be used in interop with js-libp2p
• https://github.com/libp2p/go-libp2p-relay-daemon - created for users who still need Relay V1 support, or want to run standalone RelayV2 without anything else. It is published at https://dist.ipfs.tech/#libp2p-relay-daemon and referenced in IPFS docs.

In both cases, they are not actively maintained, nor kept up-to-date, IPFS/libp2p teams are reactive (often whoever cares the most does the heavy lifting of refactoring to work with the latest go-libp2p).

This is not sustainable, delivers bad UX/DX, and is also a lost oportunity – both could act as useful examples of how to use this go-libp2p library.

Whatever we do for the first, we should also do for the second.

@MarcoPolo @marten-seemann thoughts on moving both to this repo, under examples?

• examples/test-daemon
• examples/relay-daemon