Uses GSO for UDP Packet

[scw00]

https://blog.cloudflare.com/accelerating-udp-packet-transmission-for-quic/

It is useful for tuning QUIC performance. (from QUIC slack). sendmmsg + GSO

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. Marking it stale to flag it for further consideration by the community.

[maskit]

#9037 added it.