Add snappy variant
As part of ongoing work to build a Fedora base snap under
the auspices of the Server WG, we need a specific fedora-release
variant to identify the base snap similar to how the Fedora base
container is identified.
This change provides that in the form of the 'fedora-release-snappy'
subpackage.
Signed-off-by: Neal Gompa <ngompa13@gmail.com>