Support NodaTime

Further to https://github.com/HangfireIO/Cronos/issues/36#issuecomment-817316390, is there any plan to support `NodaTime` fully, either via an additional shim package or just by including `NodaTime` in the core functionality?

For example, there's no easy way to fully implement
```csharp
ZonedDateTime? GetNextOccurence(ZonedDateTime fromZoned, bool inclusive)
```

externally as you can't guarantee there's an equivalent `System.TimeZoneInfo` for any given `NodaTime.DateTimeZone` which is more feature rich. Whereas you can largely guarantee the opposite is true.