Integrate heir-play features with Python frontend

Currently, we have both a Python frontend, and the `heir-play` package that (a) downloads the nightlies automagically and (b) exposes a cell magic for Jupyter to let you write mlir-IR directly in a Jupyter cell.

At the very least, the automagic downloading of heir_opt/heir_translate from the nightlies should be added to the Python frontend. There might also be more interesting ways to integrate them, but I'd expect we'll be very limited in what kind of "backend" we could support in Jupyer (I'd assume clang-compiling against OpenFHE isn't an option 😉)