• Created the NatsSystemClock and the NatsSystemClockProvider.
  • The NatsSystemClock is a replacement for System in regard to the clock.
  • All NatsSystemClock's public methods are static.
  • By default it uses System.nanoTime() and System.currentTimeMillis() under the covers.
  • A user can supply their own NatsSystemClockProvider. For example, for an Android add, the developer could wrap the Android SystemClock.
• Replaced System.currentTimeMillis() usages with NatsSystemClock.nanoTime() to ensure proper elapsed time in general
• Replaced all usage of System.nanoTime() with NatsSystemClock.nanoTime()

This PR is addresing #1331 and #1332. To Do (Another PR) - Replaced Task/Timers with timers using the NatsSystemClock