fix(linux): Improve version number

This change modifies the reported version number for km-config:
if km-config is installed from a debian package, the package
version will be output as well, e.g.:
`km-config version 14.0.252-beta (package version 14.0.252-1+bionic1)`

Otherwise the output will be identical to before:
`km-config version 14.0.252-beta-local`.

This change also modifies the script that sets the version number so
that builds on Jenkins are now detected in addition to TC.

This fixes #4579.