Add external memeory tests for the VK_EXT_device_memory_report extension

Add external memeory tests for the VK_EXT_device_memory_report extension

This test allocates an exportable memory and grabs the native handle
from it, then it imports the native handle twice, and verifies that the
allocate/free events are still emitted for the exportable memory as well
as verifying the proper timing of import/unimport events and the
correctness of all the callback data.

Components: Vulkan

VK-GL-CTS issue: 2266

New tests: dEQP-VK.memory.device_memory_report.external_memory.*

Change-Id: I42c08f775224735f65ceb4f3c8a77ea43d3a7ed3