Fix issues in VK_KHR_buffer_device_address tests

Fix issues in VK_KHR_buffer_device_address tests

Fixes various issues in buffer_device_address tests:
- Prefer KHR over EXT if both are available
- Check if extension is supported before checking features
- Use appropriate version of vkGetBufferDeviceAddress*
- dEQP-VK.binding_model.buffer_device_address.*convert.* requires shaderInt64

Affects:
- dEQP-VK.binding_model.buffer_device_address*
- dEQP-VK.compute.cooperative_matrix*phys*
- dEQP-VK.memory_model.*phys*
- dEQP-VK.ssbo.*phys*
- dEQP-VK.spirv_assembly.*phys*

Components: Vulkan

VK-GL-CTS Issue: 1957

Change-Id: I914d50104c08a6974e7db5902d1e88b91b2deb67