tests: Move HLSL tests to a subdirectory.

Approved-by: Giovanni Mascellani (@giomasce)
Approved-by: Francisco Casas (@fcasas)
Approved-by: Henri Verbeet (@hverbeet)
Approved-by: Alexandre Julliard (@julliard)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/248

tests/hlsl/is-front-face.shader_test

@@ -0,0 +1,36 @@
+[require]
+shader model >= 4.0
+
+[input layout]
+0 r32g32 float sv_position
+
+[vertex buffer 0]
+-2.0 -2.0
+ 2.0 -2.0
+-2.0  2.0
+ 2.0  2.0
+
+[vertex shader]
+void main(inout float4 pos : sv_position)
+{
+}
+
+[pixel shader]
+float4 main(bool face : sv_isfrontface) : sv_target
+{
+    return face ? float4(1.0f, 2.0f, 1.0f, 2.0f) : float4(0.0f, 1.0f, 0.0f, 1.0f);
+}
+
+[test]
+draw triangle strip 4
+probe all rgba (0.0, 1.0, 0.0, 1.0)
+
+[vertex buffer 0]
+-2.0 -2.0
+-2.0  2.0
+ 2.0 -2.0
+ 2.0  2.0
+
+[test]
+draw triangle strip 4
+probe all rgba (1.0, 2.0, 1.0, 2.0)