Add module for configuring consumers, senders (producer) and readers

[lhotari]

The configuration model in Apache Pulsar Java client is clumbersome. It supports a properties based configuration, but there isn't consistent support for all configuration options.

The configuration model in Reactive Java client is different. The builder approach is used, but there is a configuration object referred to as "spec" that is intended to hold the configuration value state. The reason for this is that it is more convenient to support different ways of configuration the various options in externalized configuration.
There could be modules to provide good integration with Spring Boot's configuration model and also implement ways for providing the meta data / schema for the different configuration options.

The scope of this issue is to add a Jackson based configuration module that can read json and possibly other formats that jackson supports (flat properties, yaml, etc.) and map that to the "spec" class instances which are used to configure options for consumers, senders (producer) and readers.