Generic event system

Prior to the creation of Stasis Message Bus API, the purpose of this API was to provide a generic way to share events between Asterisk modules. Once there was a need to disseminate data whose definition was provided by the producers/consumers, it was no longer possible to use the binary representation in the generic event system.

That aside, the generic event system is still useful and used by several modules in Asterisk.

• CEL uses the ast_event representation to pass information to registered backends.
• The