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This only affects javascript files and only affects things
from the prettier whitelist

This will run slowly if you don't have node_modules installed
locally (e.g., in Docker), but it will gladly attempt to
run things in Docker for you.

This adds a new githook_installer image that will install
the githook whenever a docker-compose up happens in the
repo.  It will also install the hook whenever a `yarn`
occurs locally (as a postinstall hook).

This commit should also not fail things.  For example
having unused variables is an ESLint error, but it isn't
autofixable.  It will log the error, but will otherwise
continue.  However, it will make this pretty with prettier
as well as fix any other autofixable ESLint errors.

closes CORE-2118

Test Plan:
  - Run `yarn`
  - Add some semicolons to something from the whitelist
  - git add that file
  - git commit and it will strip semicolons
  - In a dockerized Canvas:
     - docker-compose up
     - Add semicolons to a file
 ...