Improve MauiFactory performance by avoiding reflection to get base classes

[albyrock87]

Description of Change

A minor improvement to a piece of code executed on every ToHandler or ToPlatform.

Speedscope Before

Speedscope After

Extra note
I had some code ready to cache the entire Type => ServiceDescriptor(s) and make this even faster, but it breaks a unit test which honestly I don't understand the purpose of:

maui/src/Core/tests/UnitTests/Hosting/HostBuilderHandlerTests.cs

Lines 86 to 99 in 3de5be9

	public void CanChangeHandlerRegistration()
	{
	var mauiApp = MauiApp.CreateBuilder()
	.ConfigureMauiHandlers(handlers => handlers.AddHandler<ButtonStub, ButtonHandlerStub>())
	.Build();
	var specificHandler = mauiApp.Services.GetRequiredService<IMauiHandlersFactory>().GetHandler(typeof(ButtonStub));
	Assert.IsType<ButtonHandlerStub>(specificHandler);
	mauiApp.Services.GetRequiredService<IMauiHandlersFactory>().GetCollection().AddHandler<ButtonStub, AlternateButtonHandlerStub>();
	var alternateHandler = mauiApp.Services.GetRequiredService<IMauiHandlersFactory>().GetHandler(typeof(ButtonStub));
	Assert.IsType<AlternateButtonHandlerStub>(alternateHandler);
	}

[PureWeen]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).