Investigate replacing FPM with nFPM

[SwooshyCueb]

The path toward Normal and Boring packaging is a long and tedious one. In the meantime, we might be able to make our current packaging situation for externals a little better. Let's look into replacing FPM with nFPM, which will remove the need for a ruby virtual environment.

[trel]

oooh, that looks good.

[SwooshyCueb]

Looks like nFPM is a no-go, at least for now. There is no mechanism for adding arbitrary tags to RPM spec files, which we need for clang-runtime.
There may be other deficiencies.
Once I'm done with Ubuntu 24.04 support, I'm going to figure out what else is needed, and start opening issues in the upstream nFPM issue tracker for missing functionality. Depending on my findings, I may submit PRs myself.

[trel]

I like it.