add VRM scripts

Scripts/UniTask/Unit.cs

@@ -0,0 +1,41 @@
+using System;
+
+namespace UniTask
+{
+    [Serializable]
+    public struct Unit : IEquatable<Unit>
+    {
+        static readonly Unit @default = new Unit();
+
+        public static Unit Default { get { return @default; } }
+
+        public static bool operator ==(Unit first, Unit second)
+        {
+            return true;
+        }
+
+        public static bool operator !=(Unit first, Unit second)
+        {
+            return false;
+        }
+
+        public bool Equals(Unit other)
+        {
+            return true;
+        }
+        public override bool Equals(object obj)
+        {
+            return obj is Unit;
+        }
+
+        public override int GetHashCode()
+        {
+            return 0;
+        }
+
+        public override string ToString()
+        {
+            return "()";
+        }
+    }
+}