Update ASP.NET Core F# project templates to use new minimal hosting APIs in .NET 6

[DamianEdwards]

F# equivalent of #33944

The ASP.NET Core project templates included in the SDK should be updated to use the new minimal hosting APIs introduced in .NET 6 as they represent the new idiomatic way to bootstrap (configure and start) the relevant host for the majority of scenarios.

• The CreateHostBuilder method would be removed as the patterns that were previously reliant on this are no longer necessary
• The Startup class would be removed and its contents applied as applicable to the calls to WebApplicationBuilder in Program.cs