Improve checkSupport in memoryRequirements tests

Improve checkSupport in memoryRequirements tests

checkSupport Function in dEQP-VK.api.buffer_memory_requirements.*
tests were incomplete and didn't check for VK_KHR_video_queue
extension.

This CL improves the checkSupport function of those tests by adding
the extension check. This CL includes also some other minor improvements
for the checkSupport function.

Components: Vulkan

VK-GL-CTS issue: 3424

Affects:

dEQP-VK.api.buffer_memory_requirements.*

Change-Id: Ie7ca94e3f56a270d981d5538516212cbc688d801