[NativeAOT] Remove unnecessary [DynamicDependency] attributes (#18808)

This is a follow-up to #18666

This PR resolves the following warnings that I've seen in build logs
when running MySingleView with NativeAOT:

```
ILLink : warning IL2034: <Module>..cctor(): The 'DynamicDependencyAttribute' could not be analyzed. [/..../xamarin/xamarin-macios/tests/dotnet/MySingleView/MySingleView.csproj]
ILLink : warning IL2034: <Module>..cctor(): The 'DynamicDependencyAttribute' could not be analyzed. [/..../xamarin/xamarin-macios/tests/dotnet/MySingleView/MySingleView.csproj]
...
```

The generated module cctor code looks like this:

```c#
internal class <Module>
{
	[DynamicDependency("InvokeConformsToProtocol(ObjCRuntime.NativeHandle)", typeof(NSObject))]
	[DynamicDependency("Foundation.NSObject", null)]
	[DynamicDependency("ConformsToProtocol(ObjCRuntime.NativeHandle)", typeof(NSObject))]
	[DynamicDependency("Foundation.NSObject", null)]
        // ...
	static <Module>()
	{
		// ...
	}
}
```

The `[DynamicDependency("T", null)]` attributes are invalid. We could
change them to `[DynamicDependency(DynamicallyAccessedMemberTypes.None,
typeof(T))]` but I think that attribute is redundant because the type
itself is always already preserved through the attribute that precedes
it with a selector of one of its methods/fields.

tools/dotnet-linker/ApplyPreserveAttributeBase.cs

@@ -179,7 +179,12 @@ static bool IsConditionalAttribute (CustomAttribute? attribute)
 		void PreserveUnconditional (IMetadataTokenProvider provider)
 		{
 			Annotations.Mark (provider);
-			AddDynamicDependencyAttribute (provider);
+
+			// We want to add a dynamic dependency attribute to preserve methods and fields
+			// but not to preserve types while we're marking the chain of declaring types.
+			if (provider is not TypeDefinition) {
+				AddDynamicDependencyAttribute (provider);
+			}
 
 			var member = provider as IMemberDefinition;
 			if (member is null || member.DeclaringType is null)