LPS-31462 Message broadcasting in staging

Hey Julio,

A new fresh batch of code. On the long run we are creating more classes to have a support in the export import framework. Meaning of the processes would send out messages about their status, if there's an error, or a process has been completed, etc.

The first step towards that direction, creating the message object which will hold the necessary information, a level enum for the message, and a factory. Obviously the factory will make the creation of these messages easier.

I've written javadocs as well for these classes, I'm not sure if I include Jim already in the review, or you would do it when you send it to Brian, or will I do it when you send it to Brian. Anyhow, let me know.

Thanks!

Máté

cc: @KocsisDaniel