Create Python bindings for EvtGen

[spflueger]

It would be useful to have Python bindings for EvtGen phsp generator so that it can be used in TensorWaves, next to the phasespace package.

Easiest is to just wrap the the necessary c++ code with a pybind11 interface. That can be put into a separated repo and released on PyPI.

Subtasks	Estimated Effort
initial discussion	1-2 h
copy necessary evtgen c++ code	15 min
write facade code (reuse compwa)	3-5 h
write python bindings (pybind11)	1-3 h
write tests (reuse compwa)	1-2h
write docs	2-4h
setup CI and deployment	2-5h

[Estimated effort: 2-4 days]

[shenvitor]

As a side note: It should be relatively not very difficult to implement the Rambo algorithm, see here, also see here, for flat phase-space generation.

We see some event generators which are accessible
e.g.
RAMBO Generator
Phase Space (hazma.phase_space)