Verbose logging

[maBarabas]

There is a logLevel field on the FlutterReactiveBle. After setting this to LogLevel.verbose, I'm not seeing any more logging in the console.

I don't see any code using the _debugLogger member of FlutterReactiveBle. I've also looked through the native android code, and there are no logs printed from there either.

This is the commit where the logging was added: 29ad11f

It was later removed in #338. The summary at the top says no functionality changed, but the debug logging was removed.

Was verbose logging meant to be removed here, or is that a mistake? If this was on purpuse, you should also remove the left over LogLevel and Logger classes.

I would like to see the data passed in and out of the native API for debugging. It looks like this old debug logging only used to print the data passed between dart and the native plugin.

[Taym95]

I think this was mistake, PR is welcome if you want to add it.