Improve logging configuration

[nicoloboschi]

Now it's hard to understand how to configure logging for a particular component. Probably a logging section would be useful

[nicoloboschi]

It'd be very cool to have a section like this in global, overridable by single components

global:
  logging:
    level: info
    rootLevel: info
broker:
  logging:
    rootLevel: debug

ideally it would be great to provide a way to change log level for single package/class but it's not supported by pulsar without changing the log4j2.yaml file directly. Same apply for functions.

[michaeljmarshall]

I don't know of any way, but if we make the log4j2.yaml a config map, we can have the operator update the config map.