lxc: Add storage volume snapshot support
lxc: Add storage volume snapshot support

Co-authored-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@ubuntu.com>
Signed-off-by: Thomas Hipp <5f82c492b3b00e427412d216ce820707a10c51ce@canonical.com>

hallyn/lxd,atxwebs/lxd,Skarlso/lxd,mjeanson/lxd,stgraber/lxd,atxwebs/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,Skarlso/lxd,hallyn/lxd,atxwebs/lxd,hallyn/lxd,hallyn/lxd,Skarlso/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,mjeanson/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,mjeanson/lxd,Skarlso/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,atxwebs/lxd