Add test for maxVertexInputAttributes

Add test for maxVertexInputAttributes

Tests were added to verify that implementations can use as many vertex
input attributes as they advertise.

Existing vertex input tests were modified to never consume more than
one vertex input binding per vertex input attribute.

New tests:

dEQP-VK.pipeline.vertex_input.max_attributes.*

Affects:

dEQP-VK.pipeline.vertex_input.single_attribute.*
dEQP-VK.pipeline.vertex_input.multiple_attributes.*

Components: Vulkan

VK-GL-CTS issue: 261

Change-Id: I3a481618e700ccda8caa4ea00426be14867a58e5