D5143: Introduce fetch-translations build command

[Aleix Pol Gonzalez]

apol marked 3 inline comments as done.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D5143

To: apol, #frameworks, #build_system, kfunk, ltoscano, aacid, ilic
Cc: sitter