fix: HostBuilder.Build() shares LogExtensionPoint.AmbientLoggerFactory

Fixes: #3008

Context: unoplatform/uno.templates#1921

`dotnet new unoapp` templates have two patterns for `ILogger`
configuration:

 1. The *recommended* pattern, which uses Dependency Injection (DI)
    via [`.UseLogging()`][0]:

        dotnet new unoapp -preset "recommended"

 2. The "No Dependency Injection" (NoDI) pattern, which *doesn't* use
    Dependency Injection, and instead has an
    [`App.InitializeLogging()`][1] method called from [`Main()`][2]:

        dotnet new unoapp -di False

The wonderful thing is, those log *different*, non-overlapping, things.

The Dependency Injection pattern provides an `ILogger` instance to
constructors of types registered with e.g.
[`services.AddSingleton()`][3]:

	services.AddSingleton<IMyService, MyService>()
	// …
	interface IMyService;
	class MyService : IMyService {
	  public MyService(ILogger<MyService> logger) => …;
	}

The "No Dependency Injection" pattern provides `ILogger` instances from
the [`Log<T>(T)` extension method][4], which is used extensively within
Uno itself, e.g.

	// https://github.com/unoplatform/uno/blob/77c6ca0533a63be48c6bbdd830c8653e17a9b0fa/src/Uno.UI.Dispatching/Native/NativeDispatcher.cs#L146
	dispatcher.Log().Error("NativeDispatcher unhandled exception", exception);

Using only DI logging initialization will miss NoDI messages.

Using only NoDI logging initialization will miss DI messages.

In order to capture *all* `ILogger`-originated messages, *both* DI
and NoDI log initialization patterns must be used, which is *not*
done by *any* `dotnet new unoapp` templates.

Additionally, DI-based logging is *optional* -- it can be disabled
via `dotnet new unoapp -di False …` -- and thus its presence cannot
necessarily be relied upon.

Attempt to begin improving this scenario by updating
`HostBuilder.CreateServiceProvider()` (via `HostBuilder.Build()`)
to [Replace][5] the `ILoggerFactory` registration added by
`.AddLogging()` with the `ILoggerFactory` instance stored by
`Uno.Extensions.LogExtensionPoint.AmbientLoggerFactory`.

This means that *if* NoDI init is performed *before*
`HostBuilder.Build()` is invoked, then the `ILoggerFactory` instance
created as part of NoDI init is also registered with `IHost.Services`.
This in turn means that if NoDI init is performed *and not* DI init,
registered services will obtain an `ILogger` instance which follows
the NoDI init configuration.

Meaning that *only* NoDI init will be required to see *both* NoDI
*and* DI-originating messages.

[0]: https://github.com/unoplatform/uno.templates/blob/8988cac5efc444de0afeb400da1da24620b5c083/src/Uno.Templates/content/unoapp/MyExtensionsApp.1/App.recommended.cs#L81-L112
[1]: https://github.com/unoplatform/uno.templates/blob/8988cac5efc444de0afeb400da1da24620b5c083/src/Uno.Templates/content/unoapp/MyExtensionsApp.1/App.blank.cs#L115-L182
[2]: https://github.com/unoplatform/uno.templates/blob/8988cac5efc444de0afeb400da1da24620b5c083/src/Uno.Templates/content/unoapp/MyExtensionsApp.1/Platforms/Desktop/Program.cs#L10-L14
[3]: https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.dependencyinjection.servicecollectionserviceextensions.addsingleton?view=net-10.0-pp
[4]: https://platform.uno/docs/articles/logging.html#uno-logging-extensions
[5]: https://learn.microsoft.com/dotnet/api/microsoft.extensions.dependencyinjection.extensions.servicecollectiondescriptorextensions.replace?view=net-10.0-pp#microsoft-extensions-dependencyinjection-extensions-servicecollectiondescriptorextensions-replace(microsoft-extensions-dependencyinjection-iservicecollection-microsoft-extensions-dependencyinjection-servicedescriptor)

Author: jonpryor

src/Uno.Extensions.Hosting.UI/HostBuilder.cs

@@ -1,6 +1,8 @@
 // Marking as auto-generated to prevent StyleCop including this file - Taken from Microsoft.Extensions.Hosting
 // <auto-generated />
 
+using Microsoft.Extensions.DependencyInjection.Extensions;
+
 namespace Uno.Extensions.Hosting;
 
 /// <inheritdoc cref="IHostBuilder" />
@@ -241,6 +243,12 @@ private void CreateServiceProvider()
 		//services.AddOptions().Configure<HostOptions>(options => { options.Initialize(_hostConfiguration); });
 		services.AddLogging();
 
+		var ambientFactory = Uno.Extensions.LogExtensionPoint.AmbientLoggerFactory;
+		if (ambientFactory is not null)
+		{
+			services.Replace(ServiceDescriptor.Singleton(typeof(ILoggerFactory), ambientFactory));
+		}
+
 		foreach (Action<HostBuilderContext, IServiceCollection> configureServicesAction in _configureServicesActions)
 		{
 			configureServicesAction(_hostBuilderContext!, services);

src/Uno.Extensions.Hosting.UI/Uno.Extensions.Hosting.WinUI.csproj

@@ -18,6 +18,7 @@
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.Extensions.Hosting" />
+		<PackageReference Include="Uno.Core.Extensions.Logging.Singleton" />
 	</ItemGroup>
 
 	<ItemGroup Condition="'$(IsBrowserWasm)'!='true'">