Revert "Revert "java.time.Instant.toEpochMilli() fixes""

This reapplies commit ca2b1f0f.
The original commit was reverted. It had broken DateTest because
it changed the minimum/maximum Instant that is convertible to Date.
Those boundaries are undocumented; the old behavior was more
arbitrary and was never launched in Android. Therefore, it's
reasonable to just update the test.

This CL reapplies the original change and updates DateTest accordingly.

Test: DateTest
Test: CtsLibcoreTestCases
Bug: 31028374
Bug: 35245079

This reverts commit 18db57ad.

Change-Id: I8dd24ac6f0d0d5f58d2d0bb51404ba5c8ced2473