Decouple the Kestrel transport layer from Microsoft.AspNetCore.Hosting

Both **Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets** and **Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv** depend on **Microsoft.AspNetCore.Hosting** because they expose extension methods on `IWebHostBuilder`, with the move to generic host and exposing the ability to create client connections from these transports (#10872), it's odd to have this dependency.

It seems like to preserve `UseSockets` and `UseLibuv`, we'll need to have extensions methods like these somewhere, either on the `IWebHostBuilder` or on the `IServiceCollection`. It seems like we'll need to introduce new packages to that have just the code without the extensions and another one that has the wire up code (much like we have the kestrel meta package today).

cc @shirhatti @anurse