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.

gtests/Hlsl.FromFile.cpp

@@ -88,6 +88,7 @@ INSTANTIATE_TEST_CASE_P(
         {"hlsl.attribute.frag", "PixelShaderFunction"},
         {"hlsl.attribute.expression.comp", "main"},
         {"hlsl.basic.comp", "main"},
+        {"hlsl.basic.geom", "main"},
         {"hlsl.buffer.frag", "PixelShaderFunction"},
         {"hlsl.calculatelod.dx10.frag", "main"},
         {"hlsl.calculatelodunclamped.dx10.frag", "main"},