Add RPM packaging tests and RPM packaging rake task

[treydock]

Example execution:

rake package:rpm[el7] VERSION=2.0.15

The Github action just takes latest tag in git repo and uses that since the package isn't getting used, just need some version to use for building tar and passing to build script to match tar file.

Fixes #1265

[johrstrom]

I think we're good with this, I just need some clarity on why it's not pulling Source0 from GH and instead using the local tar.gz file. I even tried on 2.0.3.

Why is it using the local tar.gz instead of the remote one?

[treydock]

So the way RPMs build, even if you put Source0: https://foo.bar/1.0.0.tar.gz, the tar.gz isn't pulled from foo.bar, that part is just for reference. The 1.0.0.tar.gz must exist in SOURCE directory within build root, so either we download the tar.gz from Github or we generate it from local code, you can't have RPM build process download tar.gz files from remote sources during the build. There are tools outside the RPM build process that can parse the SourceN:... lines and bootstrap them into SOURCE directory for RPM build root and then RPM build would be run, and that's exactly what we do when we build tagged releases. For these testing purposes, we want to build RPM against local code so we build local tar.gz.

For tagged builds, this is where we take Source0: and download tar.gz: https://github.com/OSC/ondemand-packaging/blob/85fb7fce3b19c5c57431e5e6e7ccb890f632cff9/build/Rakefile#L179-L182

[johrstrom]

Thanks, I think this is a good start. I'll create follow up tickets about verification.