YAML format allows multiple sets of dependencies. MBS splits them in stream
expansion phase and output modules have probably only a single set of
dependencies. Though specification does not prevent from having multiple sets
in the output modulemd document which is put to a repository. These multiple
sets have a logical OR releation and make modular dependencies algebraically
complete.

DNF: We do not implement the OR level. And we do not want to implement it.


DECISION
========

Remove OR-level of dependencies. Keep only and AND-level.
For the sake of simplicity, "dependencies-and" end "dependencies-or" elements
will be removed and "dependency" elements moved to "dependencies-or" level.

