Add ILogger and let LoggingAdapter implement it

Also simplify LoggingAdapter by removing all LogLevel(string message), for example Warning(string message), as these can be handled by the overloads with the arguments (string format, params object[] args)
Use ILogger instead of LoggingAdapter where possible
Add and use ILogger Logging.CreateLogger()

Logging.GetLogger() is deprecated
Logging.CreateLogger() implemented as an extension method so inside actors the user can write:
private readonly ILogger _log = Context.CreateLogger();

Therefore ILogger is used instead of LoggingAdapter
IActorLogging is no longer used. It didn't provide any value previously either.

Breaking changes:
Log property on these classes has been changed from LoggingAdapter to ILogger
- FSM
- InboxActor
- RemoteWatcher