This adds pyproject.toml, needed to configure defaults for autopep8.
The file is auto-discovered in a similar way to .clang-format, other
tools could be configured here too. For now just configure autopep8 so
this can be enabled in IDE's without causing unexpected edits such as
wrapping lines over 80 columns in width.
Now autopep8 can be used from the root directory by running: autopep8 .
This uses multiple-jobs to run autopep8 over all Python scripts except
paths that are explicitly ignored in exclude defined by pyproject.toml.
Reviewed By: mont29, brecht, sybren
Ref D14686
