A QUIC implementation in pure Go Files

This release introduces client-side support for QUIC Connection Migration (server-side support was added in the last release). Clients can now probe multiple paths and switch between them mid-connection. For example, this enables seamless migration from Wi-Fi to a cellular connection when Wi-Fi connectivity deteriorates.

For details on using the new Connection Migration API, please refer to the documentation.

Breaking Changes

• The error returned from Connection.OpenStream, OpenUniStream, OpenStreamSync and OpenUniStreamSync doesn't implement net.Error anymore. Use error assertion on StreamLimitReachedError instead: [#5060]
• ClientHelloInfo was renamed to ClientInfo: [#5016]

Other Notable Changes

• Documentation improvements: [#4955] (thanks to @mark-rushakoff!), [#5047], [#5061]
• http3: reject duplicate pseudo headers: [#4993] (thanks to @pittgi!)
• Correctly handle undefined IPv4 / IPv6 preferred address values: [#4985], [#4986]
• Fix potential deadlock when OpenStreamSync context is cancelled: [#5037] (thanks to @sukunrt for a very helpful review!)
• Stateless resets are now properly detected when zero-length Connection IDs are used: [#5027]

Behind The Scenes

• As in the last couple of releases, we continued our ongoing effort to migrate away from the Ginkgo test suite (tracking issue [#3652]). The quic package is now fully migrated (#4957, [#4969], [#5033], [#5040], [#5054]). There are still ~5300 LOC of Ginkgo tests to clean up, mainly in the congestion and the http3 package.
• We've fully migrated from math/rand and golang.org/x/exp/rand to the new math/rand/v2 package: [#5044], [#5045], [#5046]