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/HostShaderCacheHeader.cs

@@ -0,0 +1,42 @@
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.Graphics.Gpu.Shader.Cache.Definition
+{
+    /// <summary>
+    /// The header of a shader program in the guest cache.
+    /// </summary>
+    [StructLayout(LayoutKind.Sequential, Pack = 0x1, Size = 0x10)]
+    struct HostShaderCacheHeader
+    {
+        /// <summary>
+        /// The count of shaders defining this program.
+        /// </summary>
+        public byte Count;
+
+        /// <summary>
+        /// Unused/reserved.
+        /// </summary>
+        public byte Reserved1;
+
+        /// <summary>
+        /// Unused/reserved.
+        /// </summary>
+        public ushort Reserved2;
+
+        /// <summary>
+        /// Size of the shader binary.
+        /// </summary>
+        public int CodeSize;
+
+        /// <summary>
+        /// Create a new host shader cache header.
+        /// </summary>
+        /// <param name="count">The count of shaders defining this program</param>
+        /// <param name="codeSize">The size of the shader binary</param>
+        public HostShaderCacheHeader(byte count, int codeSize) : this()
+        {
+            Count    = count;
+            CodeSize = codeSize;
+        }
+    }
+}