Move interop tests to libp2p/interop

[raulk]

Would that make sense, @vasco-santos?

[vasco-santos]

I would like to add more specific tests for mplex in libp2p/interop and I think that we can use these tests as a groundwork for that. The tests in this repo are not updated for more than one year, and I believe they are not being used nowadays for the released process (both by go and js) and they should live under libp2p/interop for visibility purposes.

My proposal is to create a tracking issue in libp2p/interop, and once we add the tests there in the same format as the other ones, we can remove them from here.