Support for prefetching RPMs [PoC]

[onosek]

This is the proof of concept of RPM prefetching functionality. Design concept: https://github.com/containerbuildsystem/cachi2/discussions/465

A new rpm package manager was added as a development version so --dev-package-managers flag needs to be activated.

• fetch-deps command will read the rpms lockfile and download listed packages and sources into the output directory structure. Also SBOM file will be generated (bom.json).
• inject-files command will create repofile for each arch and create repository metadata out of its RPMs for every repoid dir.

Maintainers will complete the following section

• [ ] Commit messages are descriptive enough
• [ ] Code coverage from testing does not decrease and new code is covered
• [ ] Docs updated (if applicable)
• [ ] Docs links in the code are still valid (if docs were updated)

Note: if the contribution is external (not from an organization member), the CI pipeline will not run automatically. After verifying that the CI is safe to run:

• approve GitHub Actions workflows by clicking a button
• approve the Red Hat Trusted App Pipeline container build by commenting /ok-to-test (as is the standard for Pipelines as Code)

[onosek]

• Missing unittests
• Contains some # NOTE comments - they will be removed after clarification.
• Input file source/rpms.lock.yaml won't be part of the merge. It serves just for your testing: cachi2 fetch-deps --log-level DEBUG --dev-package-managers rpm -source source --output output cachi2 inject-files --log-level DEBUG output

[tkdchen]

/ok-to-test