[Epic] HTTP/3 support in ASP.NET Core

[analogrelay]

This is a high-level tracking work item for HTTP/3 and QUIC support in ASP.NET Core. We'll add items to this as we go.

NOTE: We have no concrete plans on when we are shipping this experience yet.

(Rough) Child Items:

• Design how QUIC interacts with Bedrock (multiple streams, connection features, etc.)
• QUIC transport for Bedrock
• HTTP/3 frame parsing for Kestrel, built on top of QUIC
• Ramp up HTTP/3 interop tests #19972 Ramp up interop tests
• Define and test the end-to-end scenarios for HTTP/3 preview #19973 Define end-to-end scenarios for the preview phase

NOTE: Public APIs for QUIC are out-of-scope for this initial release in 5.0. They're still very much on our radar, but the spec is in flux and we want to focus on an end-to-end scenario that works.

@jkotalik @shirhatti @captainsafia @wtgodbe

[aL3891]

This is really really cool!
Please also consider adding httpclient (or client support in general) to the prototype work, i think a really great use case for this is inter service communication in a micro service solution (as in not using a browser).

That's something i'd like to do at least :)

[Tratcher]

@aL3891 yes we're working with the client networking folks on these prototypes.

[analogrelay]

Putting this in 5.0.0 to represent the fact that we are doing work now, and that work definitely won't land in 3.1. Doesn't mean we're committing to anything real in 5.0 yet ;).

[tmds]

@anurse I wonder how this will work .NET Core that is completely build from source. What will provide the quic implementation? Will "msquic" be open-sourced? Or something else?

cc @crummel @dagood

[tmds]

cc @omajid