tests/qtest/libqtest: add qtest_has_cpu_model() api

tests/qtest/libqtest: add qtest_has_cpu_model() api

Added a new test api qtest_has_cpu_model() in order to check availability of
some cpu models in the current QEMU binary. The specific architecture of the
QEMU binary is selected using the QTEST_QEMU_BINARY environment variable.
This api would be useful to run tests against some older cpu models after
checking if QEMU actually supported these models.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Reviewed-by: Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20240610155303.7933-3-anisinha@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>