Determine Linux package name to show in mapping

[nightlark]

The package mapping from http://security.ubuntu.com/ubuntu/dists/noble/Contents-amd64.gz isn't quite what we want... more often, the source package name used to build the package is the more "human" name (but not always! e.g. libstdc++ -> gcc)

• the source package for libstdc++ is gcc... which it's true that it is part of gcc, but libstdc++ is notable enough that it should be specifically highlighted, rather than being called gcc
• probably other name normalization for common packages we come across that should happen (libc -> glibc?)

[nightlark]

7/24 - acquiring source package names, and favors them when possible