[i18n] prepare i18n package change of cosmetic_changes-append
[i18n] prepare i18n package change of cosmetic_changes-append

cosmetic_changes-append is used by the framework itself but not by
the cosmetic_changes script. pywikibot translation packages will be
supported by the site-package too. Support both for a while.

Change-Id: I36cb993bd55a294b28291101b72c09d09f132795

wikimedia/pywikibot-core,wikimedia/pywikibot-core