Add Containerfile and build.sh to build it.

Add Containerfile and build.sh to build it.

The intent is to replace ceph-container.git, at first for ci containers
only, and eventually production containers as well.

There is code present for production containers, including
a separate "make-manifest-list.py" to scan for and glue the two
arch-specific containers into a 'manifest-list' 'fat' container,
but that code is not yet fully tested.

This code will not be used until a corresponding change to the
Jenkins jobs in ceph-build.git is pushed.

Note that this tooling does not authenticate to the container repo;
it is assumed that will be done elsewhere.  Authentication is
verified by pushing a minimal image to the requested repo.

Signed-off-by: Dan Mick <dmick@redhat.com>