Now that we have a staging directory, we can add the old-style tests from
proposal-temporal and avoid having to sync PRs across two repositories
when we convert them to test262 style.
Ms2ger wrote a script to convert them to be executable with the test262
harness, and this is the result of running that script on the remaining
Temporal.Instant tests in proposal-temporal.
More tests of other Temporal types to follow.