fix: Accept any type of date in the f function

`date-fns` functions do not accept dates formatted as strings anymore, but only date objects.
We make it so the `f` function returned by the `useI18n` hook still accepts other types of values, strings in particular.
This should help consuming libs and apps to migrate.

react/I18n/format.jsx

@@ -35,8 +35,9 @@ export const initFormat = (userLang, defaultLang = DEFAULT_LANG) => (
   date,
   formatStr
 ) => {
+  const dateObject = new Date(date)
   const locale = provideDateFnsLocale(userLang, defaultLang)
-  return format(date, formatStr, { locale })
+  return format(dateObject, formatStr, { locale })
 }
 
 export const formatLocallyDistanceToNow = date =>