Handle deprecation of kotlinx datetime `Instant` (and Clock)

[Jolanrensen]

See https://github.com/Kotlin/kotlinx-datetime/blob/master/README.md#deprecation-of-instant

Might need to use the compat version to handle the migration from kotlinx -> kotlin, such that we can convert from kotlinx classes to kotlin ones, but still default to kotlin Instants.