Salieri: shader cache (#1701)

Here come Salieri, my implementation of a disk shader cache!

"I'm sure you know why I named it that."
"It doesn't really mean anything."

This implementation collects shaders at runtime and cache them to be later compiled when starting a game.

Ryujinx.Graphics.Shader/BufferDescriptor.cs

@@ -2,8 +2,8 @@ namespace Ryujinx.Graphics.Shader
 {
     public struct BufferDescriptor
     {
-        public int Binding { get; }
-        public int Slot { get; }
+        public readonly int Binding;
+        public readonly int Slot;
 
         public BufferDescriptor(int binding, int slot)
         {