WIP: HLSL: Add GS support

This PR adds:

[maxvertexcount(n)] attributes

point/line/triangle/lineadj/triangleadj qualifiers

PointStream/LineStream/TriangleStream templatized types

Append method on above template types

RestartStrip method on above template types.

hlsl/hlslAttributes.h

@@ -48,17 +48,18 @@ namespace glslang {
         EatBranch,
         EatCall,
         EatDomain,
-        EatEarlydepthstencil,
-        EatFastopt,
+        EatEarlyDepthStencil,
+        EatFastOpt,
         EatFlatten,
-        EatForcecase,
+        EatForceCase,
         EatInstance,
-        EatMaxtessfactor,
-        EatNumthreads,
-        EatOutputcontrolpoints,
-        EatOutputtopology,
+        EatMaxTessFactor,
+        EatNumThreads,
+        EatMaxVertexCount,
+        EatOutputControlPoints,
+        EatOutputTopology,
         EatPartitioning,
-        EatPatchconstantfunc,
+        EatPatchConstantFunc,
         EatUnroll,
     };
 }