vfio: selftests: Test basic VFIO and IOMMUFD integration

vfio: selftests: Test basic VFIO and IOMMUFD integration

Add a vfio test suite which verifies that userspace can bind and unbind
devices, allocate I/O address space, and attach a device to an IOMMU
domain using the cdev + IOMMUfd VFIO interface.

Signed-off-by: Josh Hilke <jrhilke@google.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20250822212518.4156428-5-dmatlack@google.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>