Replace docker bash invocations with python-on-whales

[ianpittwood]

While developing blackbox tests for posit-dev/pti, I found a Docker wrapper that I actually enjoy using called python-on-whales. I think we should consider replacing our current bash invocations of docker with the python-on-whales implementation since it will likely reduce our maintenance overhead long-term.

I could also see python-on-whales giving us the ability to implement our own builder to sever our reliance on buildx bake invocations.