Added MarshalingBehaviorAttribute support

Sources/WindowsMetadata/MarshalingBehaviorAttribute.swift

@@ -0,0 +1,28 @@
+import DotNetMetadata
+
+/// Indicates the threading model of a Windows Runtime component.
+public enum MarshalingBehaviorAttribute: AttributeType {
+    public static var namespace: String? { "Windows.Foundation.Metadata" }
+    public static var name: String { "MarshalingBehaviorAttribute" }
+    public static var validOn: AttributeTargets { .class }
+    public static var allowMultiple: Bool { false }
+    public static var inherited: Bool { true }
+
+    public static func decode(_ attribute: Attribute) throws -> MarshalingType {
+        let arguments = try attribute.arguments
+        guard arguments.count == 1,
+            case .constant(let constant) = arguments[0],
+            case .int32(let value) = constant,
+            let marshalingType = MarshalingType(rawValue: value) else { throw InvalidMetadataError.attributeArguments }
+        return marshalingType
+    }
+}
+
+public enum MarshalingType: Int32, Hashable {
+    /// The class prevents marshaling on all interfaces.
+    case none = 1
+    /// The class marshals and unmarshals to the same pointer value on all interfaces.
+    case agile = 2
+    /// The class does not implement IMarshal or forwards to CoGetStandardMarshal on all interfaces.
+    case standard = 3
+}

Sources/WindowsMetadata/ThreadingAttribute.swift

@@ -16,4 +16,13 @@ public enum ThreadingAttribute: AttributeType {
             let threadingModel = ThreadingModel(rawValue: value) else { throw InvalidMetadataError.attributeArguments }
         return threadingModel
     }
+}
+
+public enum ThreadingModel: Int32, Hashable {
+    /// Single-threaded apartment
+    case sta = 1
+    /// Multithreaded apartment
+    case mta = 2
+    /// Both single-threaded and multithreaded apartments
+    case both = 3
 }