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.Gpu/Shader/Cache/Definition/GuestTextureDescriptor.cs

@@ -0,0 +1,15 @@
+using Ryujinx.Graphics.Gpu.Image;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.Graphics.Gpu.Shader.Cache.Definition
+{
+    /// <summary>
+    /// Mostly identical to TextureDescriptor from <see cref="Image"/> but we don't store the address of the texture and store its handle instead.
+    /// </summary>
+    [StructLayout(LayoutKind.Sequential, Size = 0x20, Pack = 1)]
+    struct GuestTextureDescriptor
+    {
+        public uint Handle;
+        internal TextureDescriptor Descriptor;
+    }
+}