Settings: Fix blank strings for some locales

New method for locale combinations that should handle all cases, including exotic ones.

This should handle any cases like

locale	file
en	en.lproj
en_GB	en_GB.lproj
pt_BR	pt_BR.lproj
de_FR	de.lproj
zh_Hans	zh_Hans.lproj
zh_Hans_FR	zh_Hans.lproj

by testing combinations of languageCode, scriptCode and regionCode if collatorIdentifier is invalid.

changed milestone to %3.3.0

added Must Fix label

added Regression label

assigned to @bubu

merged

mentioned in merge request !371 (closed)

mentioned in issue #1419 (closed)