Previously getISOFields() was used to get the exact value of the
[[Calendar]] and [[TimeZone]] internal slots, as well as to get the
reference ISO year for PlainMonthDay and reference ISO day for
PlainYearMonth.
Use calendarId and timeZoneId for the former and toString() for the
latter.
In many cases we created a TimeZone or Calendar instance from a built-in
time zone or calendar. These tests can be trivially adapted to just use
the string ID.
Following the upstream ECMA-402 change tested in the previous commit, add
test coverage for the corresponding functionality in Temporal. Fix one
test that was erroneous.
Built-in non-ISO calendars require either monthCode/day, or month/day plus
some form of year specification.
This adds test coverage for each of the categories listed in
https://github.com/tc39/proposal-temporal/issues/2664, of which some must
currently reside in the test/intl402/ folders.
We'll do this for now, then separately work on migrating all of the tests
that require a non-ISO8601 calendar but aren't dependent on it being any
particular calendar.