Migrate tests from WebHostBuilder to HostBuilder or WebApplicationBuilder

[jamescrosswell]

WebHostBuilder, IWebHost, and WebHost are obsolete which causes various warnings in our unit tests:

sentry-dotnet/test/Directory.Build.props

Lines 14 to 15 in a61ef11

	<!-- TODO: Migrate from WebHostBuilder to HostBuilder or WebApplicationBuilder -->
	<NoWarn>$(NoWarn);ASPDEPR004;ASPDEPR008</NoWarn>

As these were not trivial to resolve and the net10 branch already includes a massive amount of change, I think we should address these in a separate PR later.

Depends on:

• WIP: Add support for net10.0-rc.1 #4461

[linear]

NET-450 Migrate tests from WebHostBuilder to HostBuilder or WebApplicationBuilder