Fix Rename* functions on FspSrv, add a separate class do hold system settings on Switch

Ryujinx.Core/Settings/ColorSet.cs

@@ -0,0 +1,8 @@
+namespace Ryujinx.Core.Settings
+{
+    public enum ColorSet
+    {
+        BasicWhite = 0,
+        BasicBlack = 1
+    }
+}

Ryujinx.Core/Settings/SetSys.cs

@@ -0,0 +1,7 @@
+namespace Ryujinx.Core.Settings
+{
+    public class SetSys
+    {
+        public ColorSet ThemeColor;
+    }
+}