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/ShaderBundle.cs

@@ -39,7 +39,7 @@ namespace Ryujinx.Graphics.Gpu.Shader
 
             foreach (ShaderCodeHolder holder in Shaders)
             {
-                holder?.HostShader.Dispose();
+                holder?.HostShader?.Dispose();
             }
         }
     }