.with() should handle mutually exclusive fields (CalendarFieldKeysToIgnore)

[Manishearth]

https://tc39.es/proposal-temporal/#sec-temporal-calendarfieldkeystoignore

.with() when given a year should ignore era/eraYear and vice versa. Same for month/monthCode

test262 failures:

  'intl402/Temporal/PlainDate/prototype/with/gregorian-mutually-exclusive-fields': [FAIL],
  'intl402/Temporal/PlainDate/prototype/with/japanese-mutually-exclusive-fields': [FAIL],
  'intl402/Temporal/PlainDate/prototype/with/non-iso-calendar-fields': [FAIL],
  'intl402/Temporal/PlainDateTime/prototype/with/non-iso-calendar-fields': [FAIL],
  'intl402/Temporal/PlainMonthDay/prototype/with/non-iso-calendar-fields': [FAIL],
  'intl402/Temporal/PlainYearMonth/prototype/with/non-iso-calendar-fields': [FAIL],
  'staging/Intl402/Temporal/old/non-iso-calendars-japanese': [FAIL],
  'staging/Intl402/Temporal/old/persian-calendar': [FAIL],

[Manishearth]

Huh, I guess I'd double-filed issues