Implement CAL and RET shader instructions (#1618)

* Add support for CAL and RET shader instructions

* Remove unused stuff

* Fix a bug that could cause the wrong values to be passed to a function

* Avoid repopulating function id dictionary every time

* PR feedback

* Fix vertex shader A/B merge

Ryujinx.Graphics.Shader/IntermediateRepresentation/OperandType.cs

@@ -2,6 +2,7 @@ namespace Ryujinx.Graphics.Shader.IntermediateRepresentation
 {
     enum OperandType
     {
+        Argument,
         Attribute,
         Constant,
         ConstantBuffer,