add debian package building and upload to releases

[gittiver]

closes #874

[The-EDev]

I'm a little confused about this, typically I generate the .deb files when creating a release (using cpack IIRC), are we automating the release process?

[gittiver]

Basically it is for the release of the software.
Instead of cpack we use here cmake --build . --target package in the build directory, which should basically do the same (see https://discourse.cmake.org/t/are-the-commands-cmake-build-target-package-and-cpack-equivalent/612).
Platform specific packages are build as part of the normal build, but the upload is done only for .deb.

Upload could be restricted to release branches.