`flake8` and `black`: Fix Problems and add Actions for verification

[SmithChart]

This PR adds flake8 and black to this project.

We first set the tooling up for local use. Running make qa will run both tools and output any problems found.

Next:

• The code is reformatted using black and some odd whitespaces removed (while we are on it).
• Findings by flake8 are corrected and the imports re-sorted.

Finally this PR adds Github actions to run the tools on push and in PRs.

[SmithChart]

@hnez @jluebbe feel free to have another look.