Add qt5-qttranslations module

@aacid the module builds fine and puts the "translations" dir inside /usr/ (similar to "phrasebooks" dir from qt5-qttools module) since --datadir option is not set to qt5-qtbase module (usually distributions set it to something like /usr/share/qt but it shouldn't make a difference if applications use the recommended way to load the translations)

However, I haven't tested it with a fully built runtime since it seems like it'll take longer than a whole day to build it in my pc. Is there any bot to build it remotely so that I can download it and test it with the app that I maintain?