Fix intellisense attached property type mix match

[workgroupengineering]

To simulate the issue, install the latest build from the repository and try adding any Grid.Column element, you can see that Intellisense proposes True/False.

The behavior depends on this fragment

AvaloniaVS/CompletionEngine/Avalonia.Ide.CompletionEngine/AssemblyMetadata/MetadataConverter.cs

Lines 270 to 286 in 20556a5

	foreach (var methodDef in typeDef.Methods)
	{
	if (methodDef.Name.StartsWith("Set", StringComparison.OrdinalIgnoreCase) && methodDef.IsStatic && methodDef.IsPublic
	&& methodDef.Parameters.Count == 2)
	{
	setMethod = methodDef;
	}
	if (methodDef.IsStatic
	&& methodDef.Name.StartsWith("Get", StringComparison.OrdinalIgnoreCase)
	&& methodDef.IsPublic
	&& methodDef.Parameters.Count == 1
	&& !string.IsNullOrEmpty(methodDef.ReturnTypeFullName)
	)
	{
	getMethod = methodDef;
	}
	}

which returns the first static methods initialed by Set or Get instead of checking the full name.

This lines:

https://github.com/workgroupengineering/AvaloniaVS/blob/087973fd16142f327131f0107fb1bce73c0bd8e5/CompletionEngine/Avalonia.Ide.CompletionEngine/AssemblyMetadata/MetadataConverter.cs#L557-L566

is adding for check currect retutn type in test.

[Sorien]

typo Menthd -> Method?