Check config when checking the containers

The proposed approach allows for checking whether config
files are current, e.g. cases when the deployment was aborted after
config files were generated but before they were injected into the
containers which lead to old config staying in containers.

After this patch we can do:
  kolla-ansible genconfig
  kolla-ansible deploy-containers
and it would do what we expected rather than being a noop
in the second part.

We also lose the need to have notifies
and whens in config and handler sections respectively.
This is optimised in a separate patch.

Future work:
- optimise for large files
  - could we get away with comparing timestamps and sizes?
    container's should have a newer timestamp due to copy,
    could also preserve it

Change-Id: I1d26e48e1958f13b854d8afded4bfba5021a2dec
Closes-Bug: #1848775
Depends-On: https://review.opendev.org/c/openstack/kolla/+/773257


Co-Authored-By: Mark Goddard <mark@stackhpc.com>