Add Python linting to CI and make it easy to run

[wlach]

This issue is intended as an initial onboarding task for potential outreachy applicants. Please do not work on it unless you have completed the initial qualification task and it has been assigned to you.

We only have a minimal amount of python code so far, but we will accumulate more over time. To keep the quality level up, we should enable linting with flake8, black, and isort.

This is a somewhat non-trivial issue, as it will involve:

• Setting up circleci to run python code (it only validates javascript at the moment)
• Writing up the correct linter configuration (always harder than it seems)

Some prior art which might be helpful is the mozregression repository where I recently added some linter code:

mozilla/mozregression#575

Note however that it uses travis rather than circleci. You'll need to do some extra research to get this going with CircleCI.

[wlach]

@Riju19 will work on this (can assign when they accept the github invitation)

[Riju19]

Thanks @wlach, I'll start working on this right away