Change wire protocol name of the "multistream-lazy" variant

[tomaka]

The rust-libp2p implementation of multistream-select, in addition to the standard V1 protocol version, also supports a non-standard V1Lazy variant.
Link to the documentation.

While this variant removes a round-trip-time in many circumstances, its drawback is that it isn't compatible with the non-Rust versions of libp2p. For that reason, nobody uses it.

I suggest here that we:

• Change the wire name of V1Lazy to be the same as V1, therefore making indistinguishable from the standard one.
• Remove the fact that the listener delays the response, as it is, as far as I understand, the reason why this protocol isn't the same as the standard one. The listener should immediately send back the response to the protocol request, even though it might result in two packets.