yocto/images: Ensure that only the allowed images can be built

By making usage of the features_check bbclass, ensure that:
 * On Baremetal Stack the virtualization-image cannot be built
 * On Virtualization Stack the baremetal-image cannot be built

Issue-Id: SCM-5314
Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Change-Id: I5cf46b0c102e2a376a292c972d459ce8c46ce1ae