Apex: Refactor snapshot pipeline for other types

This patch changes snapshot related scripts to allow for more than just
the current snapshot type of "csit". This allows us to add other
snapshot types, including the functest type. The same
snapshot.properties file will be used to store information for all types
of snapshots. The snap cache folder structure will remain the same, but
hold different types of snapshots in the same folders.

These changes include renaming the URLs for the snapshot artifacts to
reflect the snapshot type, but remains backwards compatible until enough
promotions have occurred and other apex snapshot deployment scripts have
been migrated to the new format.

Change-Id: If3e47e700b5ad9c95418179042b85814fe389233
Signed-off-by: Tim Rozet <trozet@redhat.com>