Add web-transport-any crate with wrapper types for WebTransport polymorphism

[jhiatt-verkada]

No description provided.

[kixelated]

Hmm, I think this could go into web_transport. In the past I've used enum_dispatch to avoid the boilerplate, but that requires a trait.

...maybe web-transport-trait could be moved into web-transport and we use enum_dispatch to support all enabled implementations (via feature flag)? I'll try.

[kixelated]

I spent a few hours implementing a full enum for web_transport. I'm just not sure if it really accomplishes much; I need to sleep on it.

I mentioned it in the MoQ repo, but do we even need this enum? If you have moq_native return an enum instead, it can instantiate moq_lite based on the result. The really nice thing about that API is that the underlying web_transport_trait doesn't leak into the API, so it should be enough to instantiate moq_lite based on if the fallback succeeded or not.

[jhiatt-verkada]

This is no longer needed: moq-dev/moq#812