OVR_multiview: Add fb_attachment_params test

Add a test that reading the framebuffer attachment parameters described
in the OVR_multiview spec give the appropriate values.

A varied set of framebuffer attachments are configured:
 - COLOR_ATTACHMENT0: non-multiview, 2D
 - COLOR_ATTACHMENT1: non-multiview, 2D array, 1 layer (1)
 - COLOR_ATTACHMENT2: non-multiview, 2D array, all layers (0-3)
 - COLOR_ATTACHMENT3: multiview, 2D array, 1 layer (3)
 - COLOR_ATTACHMENT4: multiview, 2D array, 2 layers (1-2)
 - COLOR_ATTACHMENT5: non-multiview, 3D, 1 layer (3)

Then the following parameters are read back and validated:
 - GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_BASE_VIEW_INDEX_OVR
 - GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_NUM_VIEWS_OVR
 - GL_FRAMEBUFFER_ATTACHMENT_LAYERED (if exists)
 - GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER

Signed-off-by: James Hogan <james@albanarts.com>
Acked-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <!987>