lxd/containers_post: prepare for push support
lxd/containers_post: prepare for push support

Various parts of the code will move into the migration part.

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@canonical.com>

lxc/lxd,stgraber/lxd,mjeanson/lxd,hallyn/lxd,Skarlso/lxd,hallyn/lxd,hallyn/lxd,ollie314/lxd,ollie314/lxd,jsavikko/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,Skarlso/lxd,atxwebs/lxd,georghopp/lxd,jsavikko/lxd,lxc/lxd,pcdummy/lxd,georghopp/lxd,chrisglass/lxd,stgraber/lxd,pcdummy/lxd,mjeanson/lxd,akshaykarle/lxd,atxwebs/lxd,stgraber/lxd,erikmack/lxd,chrisglass/lxd,stgraber/lxd,chrisglass/lxd,techtonik/lxd,Skarlso/lxd,akshaykarle/lxd,stgraber/lxd,erikmack/lxd,lxc/lxd,stgraber/lxd,ollie314/lxd,hallyn/lxd,lxc/lxd,Skarlso/lxd,lxc/lxd,akshaykarle/lxd,erikmack/lxd,techtonik/lxd,atxwebs/lxd,georghopp/lxd,pcdummy/lxd,lxc/lxd,mjeanson/lxd,jsavikko/lxd,techtonik/lxd,atxwebs/lxd,hallyn/lxd