Proper i18n date/time handling (#17858)

* install date-fns-tz

* add date locale hook

* refactor formatUnixTimestampToDateTime

Use date-fns style instead of using strftime. This requires changing the i18n keys to the way date-fns represents dates (eg: "MMM d, h:mm:ss aaa"  instead of "%b %-d, %H:%M"

* refactor calendar to use new hook

* fix useFormattedTimestamp to use new formatUnixTimestampToDateTime date_format

* change i18n keys to new format

* fix timeline

* fix review

* fix explore

* fix metrics

* fix notifications

* fix face library

* clean up

web/src/pages/FaceLibrary.tsx

@@ -531,8 +531,12 @@ function TrainingGrid({
   const formattedDate = useFormattedTimestamp(
     selectedEvent?.start_time ?? 0,
     config?.ui.time_format == "24hour"
-      ? t("time.formattedTimestampWithYear.24hour", { ns: "common" })
-      : t("time.formattedTimestampWithYear.12hour", { ns: "common" }),
+      ? t("time.formattedTimestampMonthDayYearHourMinute.24hour", {
+          ns: "common",
+        })
+      : t("time.formattedTimestampMonthDayYearHourMinute.12hour", {
+          ns: "common",
+        }),
     config?.ui.timezone,
   );