agxv: expose KHR_external_memory_fd and KHR_external_semaphore_fd
These are fully implemented by common code, just need to turn the extensions on.
Some dEQPs from dEQP-VK.api.external.fence.* and dEQP-VK.api.external.semaphore.* fail due to missing nir intrinsics in agxv.
timeline_info dEQPs are skipped until the timeline semaphore issues with the kernel driver are fixed.
Signed-off-by: i509VCB git@i509.me