Start using i18next style plural in translations
Currently, there is only one plural form ("PLURAL_ENDING") used for time interval translations. That's not enough, since many languages have different plural forms for different words. I suggest that we start using the i18next plural style in the translations, like this example from Swedish, with three different plural endings:
{
...
"MINUTE": "minut",
"MINUTE_plural": "minuter",
"DAY": "dag",
"DAY_plural": "dagar",
"YEAR": "år",
"YEAR_plural": "år",
...
}
Also "ACTION"/"ACTIONS" could be changed to this format.
Since 136bcc95, empty strings will be handled by fallback to English, so for languages that actually should have an empty string here will instead incorrectly get "s" as a plural ending. That would also be fixed by this suggested change.
An extra benefit with this format is that it is supported by Weblate, at least according to their documentation. Then their translation tool would show the "*_plural" string as the plural form of the same word, like here.