We can now recognize & normalize all time zones from the IANA time zone
database and not just 'UTC', which makes the LibJS Temporal
implementation a lot more useful! Thanks to the newly added LibTimeZone,
this was incredibly easy to implement :^)
This already includes these recent editorial changes in the Temporal
spec: 27bffe1
Previously parse_time_zone_numeric_utc_offset_syntax() would return true
to indicate success when parsing a string with an invalid number of
digits in the fractional seconds part (e.g. 23:59:59.9999999999).
We need to check if the lexer has any characters remaining, and return
false if that's the case.
