text: Title: Make list of languages in Libdoc's default language selection dynamic
  Body: Libdoc got localization support in RF 7.2 (#3676) and it's possible to specify the default language from the command line. The list of available languages to be selected is currently hard-coded and missed languages what were added late in RF 7.2 release cycle. The list was updated in RF 7.2.1 (#5317), but it is still hard-coded so we need to remember to keep it updated when new languages are added. Let's make it list dynamic so that it's created based on the available languages automatically so we can forget about that.