shadertools: Prepare for new target Languages and APIs (#2465)

* shadertools: Prepare for new target Langugaes and APIs

This improves shader tools command line by adding support for target
language and api.

* Address gdkchan's comments

Ryujinx.Graphics.Shader/Translation/TargetLanguage.cs

@@ -3,6 +3,7 @@ namespace Ryujinx.Graphics.Shader.Translation
     public enum TargetLanguage
     {
         Glsl,
-        Spirv
+        Spirv,
+        Arb
     }
 }