Add support for force-compression while calling buildah

[mayukhc]

I have build_opts: --compression-format zstd --build-driver buildah specified under build-opts in build.yml, but it's ignored and layers in final image are still gzip. It's probably due to this issue - containers/buildah#4613, where buildah will skip compressing gzipped layers unless there's an additional force-compression flag.

[HastD]

It's being ignored due to a bug in BlueBuild, which is fixed in #645. Note from the documentation for buildah manifest push that --force-compression defaults to true if --compression-format is explicitly specified as a command-line option, so it's unnecessary to pass --force-compression explicitly—the problem is that --compression-format wasn't getting passed to buildah or podman at all due to the aforementioned bug.

[mayukhc]

Compression format is still gzip after the 0.9.28 cli release and using latest blue-build/github-action. Build.yml for reference.

EDIT: Changing the rechunker from hhd-dev/rechunk to build_chunked_oci now uses zstd as expected.