CMake: Translations: Build apt-all.pot and update .po files

CMake: Translations: Build apt-all.pot and update .po files

Merge all the per-domain templates into one template file using
msgcomm, stripping any line numbers in the input files, and sorting
the output per file.

This should create reasonably stable .pot and .po files that do not
change just because files move around. It should also be resilient
against some line changes, as long as one translated line is not
moved before/after another translated line.

Gbp-Dch: ignore