ISPN-4074 Only include public API in Javadoc

ISPN-4074 Introduce a custom doclet and documentation tag to selectively filter out non-public APIs
    
    - Move non-public Cache classes to org.infinispan.cache.impl
    - Move non-public CacheManager classes to org.infinispan.manager.impl

ISPN-3160 Correct JavaDoc for RemoteCacheManager Default executor pool size

https://issues.jboss.org/browse/ISPN-4074
https://issues.jboss.org/browse/ISPN-3160