added generation of python code for some of the protos and other supporting changes

[wjwwood]

This is still rough around the edges, but should unblock us.

The only thing you should need to do different for this to work is that after you build and source the sdk, you need to set up a Python virtualenv (or overwrite system packages) and install grpcio, protobuf, and retrying. If you want step by step, this is what I did:

$ python3 -m venv --system-site-packages venv
$ source ./venv/bin/activate
(venv) $ which pip
/path/to/sdk-ros_with_python_ws/venv/bin/pip
(venv) $ pip install -U grpcio protobuf retrying
(venv) $ python3 -c 'from intrinsic.world.python.object_world_client import ObjectWorldClient'
(venv) $ echo $?
0