CP-4324: Implement pool.apply_edition

Signed-off-by: John Else <john.else@citrix.com>
CP-4324: Add pool.apply_edition to the CLI

Signed-off-by: John Else <john.else@citrix.com>
CP-4321: Host edition upgrade rules

Free and XenDesktop licenses are left as is.
Advanced, Enterprise and Platinum licenses are converted to per-socket
license.
Anything else is made into a free license.

Signed-off-by: John Else <john.else@citrix.com>