1471: embassy-net: Make TcpSocket::abort() async r=Dirbaio a=mkj
This lets callers ensure that the reset packet is sent to the remote host. Otherwise there isn't a way to wait for the smoltcp stack to send the reset.
Requires changes to smoltcp to wake after the reset has been sent, see https://github.com/smoltcp-rs/smoltcp/compare/master...mkj:smoltcp:abort-wake
This commit also adds a "TCP accept" demo of the problem. Without the `.await` for abort() it gets dropped before the RST packet is emitted.
Co-authored-by: Matt Johnston <matt@ucc.asn.au>