fix(makefile): use copy rule for unmodified files

[hoinmic]

Several elements were not handled correctly in the Makefiles. This led to different behavior in different environments.
This fix applies the copy rule to all unchanged files between dist and pkg folders.
Fixes #13554

[martinpitt]

I commented in issue #13554

[hoinmic]

Questions answered in issue #13554

[hoinmic]

@martinpitt Would it be possible to start the checks/tests? Then I would have a CI feedback in this merge request.

[martinpitt]

@hoinmic: Can do, I started a debian and a fedora test; but we won't land it as such, it's too ad-hoc and duplicating webpack.

[hoinmic]

@martinpitt I think to correct the current makefiles nothing else is possible with little effort.
It corrects in its entirety all of the miss copy artifacts in all parts of the makefiles.
For some embedded devices Cockpit would be great, but if desired I can withdraw my annoying merge request.