All eventEmitters methods are not available on connections

see https://github.com/mariadb-corporation/mariadb-connector-nodejs/issues/244
actual implementation only permits 'on', 'once' and 'listeners' methods. All eventEmitters methods must be implemented.

Contrary to other connectors where private methods are available, mariadb connector has a front-end class that permit only use of API methods/properties, but with the problematic of not having eventEmitter directly available.

This must be corrected