Move generation from settingtypes out of dlg_settings_advanced

Avoids unreachable code linter warning by moving generation code
(of minetest.conf.example and settings_translation_file.cpp)
out of dlg_settings_advanced.

Due to passing the settings, also it avoids reading the settings file twice.

Instead of activating the code by changing the active if-clauses,
its activation is now done by uncommenting the loadfile() statement.