Follow-up from "Reduce the sourcing of deviceinfo in pmaports"

The following discussion from !4037 (merged) should be addressed:

• @ollieparanoid started a discussion: (+1 comment)

  Thanks for the patch, LGTM!

  Most of those do run in the regular installation, and are basically sourcing deviceinfo. So I'm wondering what's the best way to further reduce the use. I was thinking: [...]

  I would not make an extra package for it. But how about we install a script in postmarketos-base? Something like /usr/lib/source_deviceinfo or something (not sure if right path according to FHS), that scripts would source instead of sourcing deviceinfo directly.

  To ensure we don't source the file directly in future pmaports code, I recommend to add a check to .ci/grep.sh.