feat: add decoding nullable array property wrapper

Author: makinosp

Sources/VRCKit/Utils/NullableArray.swift

@@ -0,0 +1,22 @@
+//
+//  NullableArray.swift
+//
+//
+//  Created by makinosp on 2024/07/28.
+//
+
+import Foundation
+
+@propertyWrapper
+struct NullableArray<T: Decodable>: Decodable {
+    var wrappedValue: [T]
+
+    init(from decoder: Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        if container.decodeNil() {
+            self.wrappedValue = []
+        } else {
+            self.wrappedValue = try container.decode([T].self)
+        }
+    }
+}