Italian language translation plus template

[redtide]

This adds language translations capabilities.

There is a new CMake PROJECT_TRANSLATIONS_UPDATE option to choose if to update translation source files when building (disabled by default to avoid to annoy when making other code changes).

It seems Qt6 have no such possibility to update the sources, or I haven't got yet how it works, but at least the translation is made in the build directory as it should.

This can be merged before or after the other PRs, I'll manage the conflicts as needed.