Removed NioTSO client and server

- NioTSO client isn't needed because we're using RayLib
- Added FreeSO's API server to handle most backend operations

server/tso.common/Rendering/Framework/IO/IDepthProvider.cs

@@ -0,0 +1,10 @@
+namespace FSO.Common.Rendering.Framework.IO
+{
+    /// <summary>
+    /// Represents an object that has depth
+    /// </summary>
+    public interface IDepthProvider
+    {
+        float Depth { get; }
+    }
+}