Explore moving `zeek.hh` into Zeek

[J-Gras]

@Neverlord pointed out that the zeek.hh could move into Zeek to fully decouple Zeek and broker. As far as I can tell, this would require the python bindings as well as some testing to move as well.

[Neverlord]

As far as I can tell, this would require the python bindings as well as some testing to move as well.

I wouldn't move the bindings. I'd say this ticket is simply blocked by #303. Once the bindings are gone, there's no technical reason anymore for the zeek.hh header to stay in the Broker code base and we can instead move to over to the Zeek side.