Following up on the [loose end from the initial
PR](https://github.com/google/bumble/pull/207#discussion_r1278015116),
we can avoid accessing the Python company id map at runtime by doing
code gen ahead of time.
Using an example to do the code gen avoids even the small build slowdown
from invoking the code gen logic in build.rs, but more importantly,
means that it's still a totally boring normal build that won't require
any IDE setup, etc, to work for everyone. Since the company ID list
changes rarely, and there's a test to ensure it always matches, this
seems like a good trade.
This contains Rust wrappers around enough of the Python API to implement Rust versions of the `battery_client` and `run_scanner` examples. The goal is to gather feedback on the approach, and of course to show that it is possible.
The module structure mirrors that of the Python. The Rust API is not optimally Rust-y, but given the constraints of everything having to delegate to Python, it's at least usable.
Notably, this does not yet solve the packaging problem: users must have an appropriate virtualenv, libpython, etc. [PyOxidizer](https://github.com/indygreg/PyOxidizer) may be a viable path there.
