Added flake8 linting

Description

This MR implements a flake8 linting job that checks all of the python code for badness. At the moment the new /.flake8 file restricts the checks to

• unused imports
• trailing whitespace

I would like to expand these gradually over time to improve the requirements on code quality.

API Changes and Justification

Backwards Compatible Changes

• This change introduces no API changes
• This change adds new API calls

Backwards Incompatible Changes

• This change modifies an existing API
• This change removes an existing API

If any of the Backwards Incompatible check boxes are ticked please provide a justification why this change is necessary and why it needs to be done in a backwards incompatible way.

Review Status

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