Added 'using' field invocation support to debugger

IDE/Tests/Test1/src/UsingFields.bf

@@ -0,0 +1,43 @@
+#pragma warning disable 168
+
+using System;
+
+namespace IDETest
+{
+	class UsingFields
+	{
+		struct Vector2Int
+		{
+		    [Union]
+			struct XWidth
+			{
+				public int x;
+				public int width;
+
+				public int GetX() => x;
+			}
+		    [Union] struct YHeight : this(int y, int height);
+
+		    public using XWidth xWidth;
+		    public using YHeight yHeight;
+		}
+
+		struct TestVec : Vector2Int
+		{
+		}
+
+		public static void Test()
+		{
+			Vector2Int v0;
+			v0.x = 123;
+			v0.y = 234;
+
+			TestVec v1;
+			v1.x = 345;
+			v0.y = 456;
+
+			//Test_Start
+			int v = v0.GetX();
+		}
+	}
+}