[xaml] fix x:Array and x:Double in Release mode (dotnet#14546)

Fixes: dotnet#9422
Context: https://github.com/dotnet/maui/blob/51df629f946122945cee8f57baed80eb48e45c4e/src/Controls/src/Core/Properties/AssemblyInfo.cs#L79

In `Microsoft.Maui.Core.dll`, the default `x` namespace is defined as:

    [assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2009/xaml", "System", AssemblyName = "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]

The problem being that in apps on iOS and Android where
`PublishTrimmed` is `true`, `mscorlib.dll` will get trimmed away and
callsites will use `System.Private.CoreLib.dll` instead.

This is very much related to the issue fixed in 880ce09.

Unfortunately, my fix wasn't sufficient, because the `AssemblyName`
name in this case is the full name:

    AssemblyName = "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"

To solve the issue, let's also check for `StartsWith("mscorlib,")`.

We *could* add a new `XmlnsDefinition`, but this doesn't feel right:

    [assembly: XmlnsDefinition("http://schemas.microsoft.com/winfx/2009/xaml", "System", AssemblyName = "System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]

It doesn't make sense for a "private" assembly to appear in XAML
intellisense.

I also moved these tests to a new `XamlTests` class, as it didn't
really make sense to put them with `RadioButton` tests.

Note that these new tests wouldn't fail until we start running device
tests in `Release` mode:

dotnet#14392

src/Controls/src/Xaml/XmlTypeXamlExtensions.cs

@@ -84,7 +84,7 @@ static class XmlTypeXamlExtensions
 					potentialTypes.Add(new(typeName, xmlnsDefinitionAttribute.ClrNamespace, xmlnsDefinitionAttribute.AssemblyName));
 
 					// As a fallback, for assembly=mscorlib try assembly=System.Private.CoreLib
-					if (xmlnsDefinitionAttribute.AssemblyName == "mscorlib")
+					if (xmlnsDefinitionAttribute.AssemblyName == "mscorlib" || xmlnsDefinitionAttribute.AssemblyName.StartsWith("mscorlib,", StringComparison.Ordinal))
 					{
 						potentialTypes.Add(new(typeName, xmlnsDefinitionAttribute.ClrNamespace, "System.Private.CoreLib"));
 					}

src/Controls/tests/DeviceTests/Controls.DeviceTests.csproj

@@ -52,7 +52,7 @@
     <Compile Remove="**\*.Windows.cs" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Update="Elements\RadioButton\RadioButtonUsing.xaml.cs">
+    <Compile Update="Xaml\RadioButtonUsing.xaml.cs">
       <DependentUpon>%(Filename)</DependentUpon>
     </Compile>
   </ItemGroup>

src/Controls/tests/DeviceTests/Elements/RadioButton/RadioButtonTests.cs

@@ -41,34 +41,5 @@ public async Task IsCheckedInitializesCorrectly(bool isChecked)
 			Assert.Equal(expectedValue, valuesSecond.PlatformViewValue);
 		}
 #endif
-
-		[Fact("Parsed XAML can use mscorlib")]
-		public void Namespace_mscorlib_Parsed()
-		{
-			var page = new ContentPage();
-			page.LoadFromXaml(
-				"""
-				<?xml version="1.0" encoding="UTF-8"?>
-				<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
-					xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
-					xmlns:sys="clr-namespace:System;assembly=mscorlib">
-					<RadioButton>
-						<RadioButton.Value>
-							<sys:Int32>1</sys:Int32>
-						</RadioButton.Value>
-					</RadioButton>
-				</ContentPage>
-				""");
-			Assert.IsType<RadioButton>(page.Content);
-			Assert.Equal(1, ((RadioButton)page.Content).Value);
-		}
-
-		[Fact("Compiled XAML can use mscorlib")]
-		public void Namespace_mscorlib_Compiled()
-		{
-			var page = new RadioButtonUsing();
-			Assert.IsType<RadioButton>(page.Content);
-			Assert.Equal(1, ((RadioButton)page.Content).Value);
-		}
 	}
 }

src/Controls/tests/DeviceTests/Elements/RadioButton/RadioButtonUsing.xaml → src/Controls/tests/DeviceTests/Xaml/RadioButtonUsing.xaml

@@ -3,6 +3,16 @@
 	xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
 	xmlns:sys="clr-namespace:System;assembly=mscorlib"
 	x:Class="Microsoft.Maui.DeviceTests.RadioButtonUsing">
+	<ContentPage.Resources>
+		<ResourceDictionary>
+			<x:Array Type="{x:Type x:String}" x:Key="MyArray">
+				<x:String>Foo</x:String>
+				<x:String>Bar</x:String>
+				<x:String>Baz</x:String>
+			</x:Array>
+			<x:Double x:Key="MyNumber">42</x:Double>
+		</ResourceDictionary>
+	</ContentPage.Resources>
 	<ContentPage.Content>
 		<RadioButton>
 			<RadioButton.Value>

src/Controls/tests/DeviceTests/Xaml/XamlTests.cs

@@ -0,0 +1,98 @@
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+using Xunit;
+
+namespace Microsoft.Maui.DeviceTests
+{
+	public class XamlTests
+	{
+		[Fact("Parsed XAML can use mscorlib")]
+		public void Namespace_mscorlib_Parsed()
+		{
+			var page = new ContentPage();
+			page.LoadFromXaml(
+				"""
+				<?xml version="1.0" encoding="UTF-8"?>
+				<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+					xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+					xmlns:sys="clr-namespace:System;assembly=mscorlib">
+					<RadioButton>
+						<RadioButton.Value>
+							<sys:Int32>1</sys:Int32>
+						</RadioButton.Value>
+					</RadioButton>
+				</ContentPage>
+				""");
+			Assert.IsType<RadioButton>(page.Content);
+			Assert.Equal(1, ((RadioButton)page.Content).Value);
+		}
+
+		[Fact("Compiled XAML can use mscorlib")]
+		public void Namespace_mscorlib_Compiled()
+		{
+			var page = new RadioButtonUsing();
+			Assert.IsType<RadioButton>(page.Content);
+			Assert.Equal(1, ((RadioButton)page.Content).Value);
+		}
+
+		[Fact("Parsed XAML can use x:Array")]
+		public void x_Array_Parsed()
+		{
+			var page = new ContentPage();
+			page.LoadFromXaml(
+				"""
+				<?xml version="1.0" encoding="UTF-8"?>
+				<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+					xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+					xmlns:sys="clr-namespace:System;assembly=mscorlib">
+					<ContentPage.Resources>
+						<ResourceDictionary>
+							<x:Array Type="{x:Type x:String}" x:Key="MyArray">
+								<x:String>Foo</x:String>
+								<x:String>Bar</x:String>
+								<x:String>Baz</x:String>
+							</x:Array>
+						</ResourceDictionary>
+					</ContentPage.Resources>
+				</ContentPage>
+				""");
+			string[] array = page.Resources["MyArray"] as string[];
+			Assert.Equal(new[] { "Foo", "Bar", "Baz" }, array);
+		}
+
+		[Fact("Compiled XAML can use x:Array")]
+		public void x_Array_Compiled()
+		{
+			var page = new RadioButtonUsing();
+			string[] array = page.Resources["MyArray"] as string[];
+			Assert.Equal(new[] { "Foo", "Bar", "Baz" }, array);
+		}
+
+		[Fact("Parsed XAML can use x:Double")]
+		public void x_Double_Parsed()
+		{
+			var page = new ContentPage();
+			page.LoadFromXaml(
+				"""
+				<?xml version="1.0" encoding="UTF-8"?>
+				<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+					xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+					xmlns:sys="clr-namespace:System;assembly=mscorlib">
+					<ContentPage.Resources>
+						<ResourceDictionary>
+							<x:Double x:Key="MyNumber">42</x:Double>
+						</ResourceDictionary>
+					</ContentPage.Resources>
+				</ContentPage>
+				""");
+			Assert.Equal(42d, page.Resources["MyNumber"]);
+		}
+
+		[Fact("Compiled XAML can use x:Double")]
+		public void x_Double_Compiled()
+		{
+			var page = new RadioButtonUsing();
+			Assert.Equal(42d, page.Resources["MyNumber"]);
+		}
+	}
+}