Calling UdpStocketState::set_gro from quinn

[stormshield-fabs]

We are trying to update our dependency on quinn and would like to re-enable GRO on Windows, since we haven't encountered the problems described in #2041 (yet..?).

#2092 introduced the "off by default" behavior and a UdpSocketState::set_gro setter, but it looks like it cannot be easily called from quinn directly, because we never have access to this structure.

I've researched different options and would like to have some feedback about the best way to move forward:

1. we could add a set_gro method on the AsyncUdpSocket trait
2. if this is not acceptable for quinn (because it leaks a lower-level abstraction), the user could create a new runtime type and override Runtime::wrap_udp_socket to instantiate the UdpSocketState and call set_gro before returning the dyn AsyncUdpSocket.

@djc @mxinden @Ralith

[Ralith]

The intended workflow is to customize the runtime, yeah.

[mxinden]

We are trying to update our dependency on quinn and would like to re-enable GRO on Windows, since we haven't encountered the problems described in #2041 (yet..?).

Great to see more experimentation with the Windows API. Firefox Nightly still disables it due to the issues in #2041. We have reached out to Microsoft but haven't received a response. Please keep us posted @stormshield-fabs.