Deprecating WebHostBuilder, IWebHost, and WebHost

[BrennanConroy]

Discussion for announcement aspnet/Announcements#526

[julealgon]

Why not deprecate HostBuilder as well? Don't you want everyone to move to the new HostApplicationBuilder-based API?

I don't see a point in maintaining anything other than the new HostApplicationBuilder approach. It is superior to the previous method in every way. Having both available is quite confusing.

[martincostello]

FWIW, I would have had to refactor a lot more tests in some projects if that had been deprecated too 😅

[davidfowl]

The new interface IHostApplicationBuilder exists in .NET 9 only so it's tough to deprecate HostBuilder and IHostBuilder because many people have never used IHostApplicationBuilder. Going forward though we'll recommand HostApplicationBuilder and IHostApplicationBuilder

[julealgon]

Fair enough. Thanks @davidfowl .