Fix sparse cubemap array tests issues

Fix sparse cubemap array tests issues

Add cubeMapArrayRefZDef, a new shader token used as <compare>
parameters on some shadow cube map array texture instructions

Add <CUBE_REFZ_DEF> to some FunctionToken argument list definitions.
It will be replaced by the value of cubeMapArrayRefZDef.

Copy the depth reference value to s.cubeMapArrayRefZDef when we
generate the shader tokens

Change the way cube map array texture coordinate are computed in
the shader to support array with more than 6 layers

Specify that textureGradClampARB on shadow cubemap array is not
supported

Generate cube map array texture coordinate attributes as a vec4
with different coordinate for each layer

Affects:

KHR-GL45.sparse_texture2_tests.*
KHR-GL45.sparse_texture_clamp_tests.*

Components: OpenGL

VK-GL-CTS issue: 445

Change-Id: Ia9fb2240396ab4a34dd697d0b96985da35dfe802