tests/functional: add hypervisor test for aarch64

tests/functional: add hypervisor test for aarch64

This is a simple test case that runs an image with kvmtool and
kvm-unit-tests which can validate virtualisation works. This is useful
for exercising TCG but can also be applied to any nested virt setup
which is why it doesn't specify an accelerator.

Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-ID: <20250725154517.3523095-7-alex.bennee@linaro.org>