Embedding the registry configuration into OSBS config itself is
simple, but makes it impossible to reuse the same configuration for
multiple different composes.
A nice example is a nightly pushing images to a testing registry, and
production compose building the same images but pushing to staging
location. The original design requires duplication of all the
configuration just because registries are different.
With this option, the push information is stored in a separate option as
a mapping from NVR patterns to arbitrary data. The patterns are used to
match finished builds to registry.
The old configuration is marked as deprecated in code and will
eventually be removed. The deprecation handling in config validation
does not allow emitting warnings for nested values.
JIRA: COMPOSE-3394
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>