[3dprinter-general] Gitlab CI on Salsa for Debian packages

[Gregor Riepl]

Hi 3D printers.

The Salsa team has prepared package build CI scripts for GitLab that can be
dropped into every project on Salsa easily: [1]

I have taken the liberty to add debian/salsa-ci.yml to all the Cura packages
already, namely cura, cura-engine, libsavitar, libarcus, uranium and
fdm-materials.

There is also some discussion on a convention for naming the file, but it
looks like debian/salsa-ci.yml will be adopted by several teams: [2]

Please take a look and consider adding the CI pipeline to your packages.

Regards,
Gregor