lxd/storage/backend/lxd: Updates CreateInstanceFromBackup to populate creation date
lxd/storage/backend/lxd: Updates CreateInstanceFromBackup to populate creation date

Uses either volume info or instance info in that order depending on what is available.

Signed-off-by: Thomas Parrott <6b778ce645fb0e3dde76d79eccad490955b1ae74@canonical.com>

lxc/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,lxc/lxd,stgraber/lxd