Implement shader HelperThreadNV (#2163)

* Implement shader HelperThreadNV

* Bump shader cache version

* Use gl_HelperInvocation since its supported across all vendors

* Nit

Ryujinx.Graphics.Shader/Instructions/InstEmitMove.cs

@@ -63,6 +63,11 @@ namespace Ryujinx.Graphics.Shader.Instructions
                 // TODO: Use value from Y direction GPU register.
                 case SystemRegister.YDirection: src = ConstF(1); break;
 
+                case SystemRegister.ThreadKill: src = context.Config.Stage == ShaderStage.Fragment
+                    ? Attribute(AttributeConsts.ThreadKill)
+                    : Const(0);
+                    break;
+
                 case SystemRegister.ThreadId:
                 {
                     Operand tidX = Attribute(AttributeConsts.ThreadIdX);