MINOR: quic: implement BBR congestion control algorithm for QUIC

MINOR: quic: implement BBR congestion control algorithm for QUIC

Implement the version 3 of BBR for QUIC specified by the IETF in this draft:

https://datatracker.ietf.org/doc/draft-ietf-ccwg-bbr/

Here is an extract from the Abstract part to sum up the the capabilities of BBR:

BBR ("Bottleneck Bandwidth and Round-trip propagation time") uses recent
measurements of a transport connection's delivery rate, round-trip time, and
packet loss rate to build an explicit model of the network path. BBR then uses
this model to control both how fast it sends data and the maximum volume of data
it allows in flight in the network at any time. Relative to loss-based congestion
control algorithms such as Reno [RFC5681] or CUBIC [RFC9438], BBR offers
substantially higher throughput for bottlenecks with shallow buffers or random
losses, and substantially lower queueing delays for bottlenecks with deep buffers
(avoiding "bufferbloat"). BBR can be implemented in any transport protocol that
supports packet-delivery acknowledgment. Thus far, open source implementations
are available for TCP [RFC9293] and QUIC [RFC9000].

In haproxy, this implementation is considered as still experimental. It depends
on the newly implemented pacing feature.

BBR was asked in GH #2516 by @KazuyaKanemura, @osevan and @kennyZ96.