A new ICMPResponder interface is introduced to provide different
implementations of how the ICMP flows should return to the QUIC
connection muxer.
Improves usages of netip.AddrPort to leverage the embedded zone
field for IPv6 addresses.
Closes TUN-8640
The current supervisor serves the quic connection by performing all of the following in one method:
1. Dial QUIC edge connection
2. Initialize datagram muxer for UDP sessions and ICMP
3. Wrap all together in a single struct to serve the process loops
In an effort to better support modularity, each of these steps were broken out into their own separate methods that the supervisor will compose together to create the TunnelConnection and run its `Serve` method.
This also provides us with the capability to better interchange the functionality supported by the datagram session manager in the future with a new mechanism.
Closes TUN-8661
Devin Carr