Add reusable lint workflow

[benjeffery]

[codecov-commenter]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 96.85%. Comparing base (37cda03) to head (c9b755b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #396   +/-   ##
=======================================
  Coverage   96.85%   96.85%           
=======================================
  Files           8        8           
  Lines         794      794           
  Branches      150      150           
=======================================
  Hits          769      769           
  Misses         15       15           
  Partials       10       10           

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[benjeffery]

Just realised this repo doesn't have any linting. This is what it would look like to add - there are many issues to fix to make the lint pass. In the other tskit repos I have sometimes found real issues with this so might be worth doing, but I don't have time right now.