Merge changes Ia3d9e7e3,Ie2e264e9,I8767e4f9,I78716099

* changes:
  rusty-packets: generate a file that's ready for content
  rusty-packets: move some cpp generation to raw strings, for clarity
  rusty-packets: stub out rust generation function
  rusty-packets: move C++ and pybind11 to their own file