Provide RPM support for s390x platform

[cfilleke]

Provide RPM support for s390x platform as described in issue #3198
Is your feature request related to a problem? Please describe:
Add support for bazeldnf to maintain the rpm lists for s390x in BUILD.bazel

Describe the solution you'd like:

Add configurations necessary for bazeldnf to generate the rpm lists in WORKSPACE and BUILD.bazel, using the information for how to maintain these lists in .bazelrc, repo.yaml and hack/build/rpm-defs.sh as described in #3089 and #3090

Describe alternatives you've considered:
An alternative approach, which we've also been pursuing, would be to provide all the changes necessary for s390 builds in one PR; there are many moving parts to this, and the CI/CD needs to be installed on an s390x host to test the full set of changes.

Additional context:

Once the CI/CD system for s390x goes live, the full cross-compiled build for s390x CDI can, too.

The strategy we're choosing is to essentially cherry-pick changes that will run and be smoke tested in the x86-based CI/CD system, to reduce the risk when the PR for the full s390x build-and-test system is merged.

[cfilleke]

Suggested Test:

make rpm-deps will conduct a smoke test -- that the additions do not break the build and produce the expected result: rpm list updates in the WORKSPACE file, now with rpms for s390x architecture!