[Java.Interop] suppress IL3050 with #pragma (#1201)

Context: dotnet/android#8758 (comment)
Context: #1192
Context: 2197579

In 7d1e705 and b8f6f88, we suppressed IL3050, an AOT-related
warning with:

	// FIXME: #1192
	[UnconditionalSuppressMessage ("AOT", "IL3050")]
	// Problematic code here

We don't immediately *plan* to support NativeAOT on Android in .NET 9,
so it would be nice if we could suppress the warning *for now*.
However, if/when anyone tried to use this code in a NativeAOT context
such as 2197579, they *should* get a warning (but didn't).

We should instead use:

	// FIXME: #1192
	#pragma warning disable IL3050
	// Problematic code here
	#pragma warning restore IL3050

This will prevent us from introducing new `IL3050` and related
warnings, but if anyone consumes `Java.Interop.dll` from NativeAOT
they will see the warning.

This (re-)introduces IL3050 warnings in the build for
`samples/Hello-NativeAOTFromJNI` (2197579):

	% dotnet publish -c Release -r osx-x64
	…
	…/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs(665): AOT analysis warning IL3050: Java.Interop.JniRuntime.JniValueManager.<GetObjectArrayMarshaler>g__MakeGenericMethod|41_0(MethodInfo,Type): Using member 'System.Reflection.MethodInfo.MakeGenericMethod(Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.
	…/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs(381): AOT analysis warning IL3050: Java.Interop.JniRuntime.JniValueManager.<GetInvokerType>g__MakeGenericType|31_1(Type,Type[]): Using member 'System.Type.MakeGenericType(Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.
	…/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs(789): AOT analysis warning IL3050: Java.Interop.JavaPeerableValueMarshaler.CreateParameterToManagedExpression(JniValueMarshalerContext,ParameterExpression,ParameterAttributes,Type): Using member 'System.Linq.Expressions.Expression.Call(Expression,String,Type[],Expression[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. Calling a generic method requires dynamic code generation. This can be suppressed if the method is not generic.
	…/src/Java.Interop/Java.Interop/JniRuntime.JniTypeManager.cs(284): AOT analysis warning IL3050: Java.Interop.JniRuntime.JniTypeManager.MakeGenericType(Type,Type): Using member 'System.Type.MakeGenericType(Type[])' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The native code for this instantiation might not be available at runtime.
	…/src/Java.Interop/Java.Interop/JniRuntime.JniTypeManager.cs(277): AOT analysis warning IL3050: Java.Interop.JniRuntime.JniTypeManager.MakeArrayType(Type): Using member 'System.Type.MakeArrayType()' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available.

src/Java.Interop/Java.Interop/JniRuntime.JniTypeManager.cs

@@ -271,14 +271,18 @@ protected virtual IEnumerable<string> GetSimpleReferences (Type type)
 			static  readonly    Type[]      EmptyTypeArray      = Array.Empty<Type> ();
 			const string NotUsedInAndroid = "This code path is not used in Android projects.";
 
-			// FIXME: https://github.com/xamarin/java.interop/issues/1192
-			[UnconditionalSuppressMessage ("AOT", "IL3050", Justification = NotUsedInAndroid)]
-			static Type MakeArrayType (Type type) => type.MakeArrayType ();
+			static Type MakeArrayType (Type type) =>
+				// FIXME: https://github.com/xamarin/java.interop/issues/1192
+				#pragma warning disable IL3050
+				type.MakeArrayType ();
+				#pragma warning restore IL3050
 
-			// FIXME: https://github.com/xamarin/java.interop/issues/1192
 			[UnconditionalSuppressMessage ("Trimming", "IL2055", Justification = NotUsedInAndroid)]
-			[UnconditionalSuppressMessage ("AOT",      "IL3050", Justification = NotUsedInAndroid)]
-			static Type MakeGenericType (Type type, Type arrayType) => type.MakeGenericType (arrayType);
+			static Type MakeGenericType (Type type, Type arrayType) =>
+				// FIXME: https://github.com/xamarin/java.interop/issues/1192
+				#pragma warning disable IL3050
+				type.MakeGenericType (arrayType);
+				#pragma warning restore IL3050
 
 			[UnconditionalSuppressMessage ("Trimming", "IL2073", Justification = "Types returned here should be preserved via other means.")]
 			[return: DynamicallyAccessedMembers (MethodsConstructorsInterfaces)]

src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs

@@ -370,15 +370,16 @@ static Type GetPeerType ([DynamicallyAccessedMembers (Constructors)] Type type)
 				static Type? AssemblyGetType (Assembly assembly, string typeName) =>
 					assembly.GetType (typeName);
 
-				// FIXME: https://github.com/xamarin/java.interop/issues/1192
 				[UnconditionalSuppressMessage ("Trimming", "IL2055", Justification = makeGenericTypeMessage)]
-				[UnconditionalSuppressMessage ("AOT",      "IL3050", Justification = makeGenericTypeMessage)]
 				[return: DynamicallyAccessedMembers (Constructors)]
 				static Type MakeGenericType (
 						[DynamicallyAccessedMembers (Constructors)]
 						Type type,
 						Type [] arguments) =>
+					// FIXME: https://github.com/xamarin/java.interop/issues/1192
+					#pragma warning disable IL3050
 					type.MakeGenericType (arguments);
+					#pragma warning restore IL3050
 
 				Type[] arguments = type.GetGenericArguments ();
 				if (arguments.Length == 0)
@@ -657,11 +658,12 @@ static JniValueMarshaler GetObjectArrayMarshaler (Type elementType)
 			{
 				const string makeGenericMethodMessage = "This code path is not used in Android projects.";
 
-				// FIXME: https://github.com/xamarin/java.interop/issues/1192
 				[UnconditionalSuppressMessage ("Trimming", "IL2060", Justification = makeGenericMethodMessage)]
-				[UnconditionalSuppressMessage ("AOT",      "IL3050", Justification = makeGenericMethodMessage)]
 				static MethodInfo MakeGenericMethod (MethodInfo method, Type type) =>
+					// FIXME: https://github.com/xamarin/java.interop/issues/1192
+					#pragma warning disable IL3050
 					method.MakeGenericMethod (type);
+					#pragma warning restore IL3050
 
 				Func<JniValueMarshaler> indirect = GetObjectArrayMarshalerHelper<object>;
 				var reifiedMethodInfo = MakeGenericMethod (