Include time zones in WX weather zone data

Some NWS products, such as forecasts and other alerts, have
expiration times marked relative to the issuing authority's local
time zone. In preparation for being able to calculate expirations
accurately relative to the user's local time, embed IANA TZDB
compliant identifiers in all WX weather zone definitions, translated
from their NWS time zone codes.

Correlation files are all updated because of amending overrides
accordingly.

overrides.conf

@@ -1627,4 +1627,5 @@ location = None
 centroid = (0.3897902, 1.9928751)
 comment = suggested by Bill Agee
 description = Hong Kong Observatory
+tz = Asia/Hong_Kong
 zone_forecast = https://www.hko.gov.hk/textonly/v2/forecast/nday.htm