Use Swift's time types

[yim-lee]

Resolves #955

[ktoso]

are these correct?

[yim-lee]

Hmm I think so (and there are tests)? It used to be Deadline(Int64.max).

[ktoso]

I checked and these may end up with problematic edge cases...

It used to be that "distant future" was the absolute max value possible, but now that isn't it:

  5> (Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max)).components
$R4: (seconds: Int64, attoseconds: Int64) = {
  seconds = 18446744073
  attoseconds = 709551614000000000
}
  6> (Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max)).components
$R5: (seconds: Int64, attoseconds: Int64) = {
  seconds = 27670116110
  attoseconds = 564327421000000000
}
  7> (Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max)).components
$R6: (seconds: Int64, attoseconds: Int64) = {
  seconds = 36893488147
  attoseconds = 419103228000000000
}
  8> (Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max)).components
$R7: (seconds: Int64, attoseconds: Int64) = {
  seconds = 46116860184
  attoseconds = 273879035000000000
}
  9> (Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max) + Duration.nanoseconds(Int64.max)).components
$R8: (seconds: Int64, attoseconds: Int64) = {
  seconds = 55340232221
  attoseconds = 128654842000000000
}

I think we may need to switch to Duration? and use nil as "potentially infinite"?

In other words we need to take care that the isEffectivelyInfinite works well... it is same as not having a timeout in most cases to be honest, so let's move to Duration? if that can work out?

[ktoso]

Strike all that I tried it out and it works out since we cap inside the .nanoseconds

Thank you!

[ktoso]

Looks great, only concern about potentially needing to mark extensions on Duration and the typealias internal so folks don't get upset we're adding public API to "not our type".