mplex: streams not `reset`

[arnetheduck]

When a handler doesn't close a stream (per #762 or because it raises an exception or any other reason), in mplex it makes sense to send a reset to the other side indicating that the handler did not successfully complete the request.

reset is also not exposed to "normal" connections - when there's an error, we should ideally reset the stream instead of closing it with a regular close.

When the other side sends a reset (possibly also a regular close?) after we closed a stream, currently we log:

Unexpected bytes while waiting for EOF     topics="libp2p lpstream" tid=321929 s=632c7df19a1ed3b54f70c084

These are actually the mplex reset bytes coming through - this should be handled more gracefully because the bytes are actually expected - possibly by differentiating with a different exception.