Checklist: drop eslint for exercises

[SleeplessByte]

Per #589,

• move eslint config from root package.json into root .eslintrc
• remove all eslint dependencies from exercise-level package.json
• fix CI check to ignore eslint discrepancy between root and exercise-level package.json
• (optional): add script to add eslint:recommended to exercise-level package.json on "deploy".

[ericrobinsondev]

I'm happy to take this one, but I'm new to contributing so I'll need some direction on the third checkbox.

[SleeplessByte]

Hi @drericrobinson; this is in the works! However we could use a lot of help here.

[SleeplessByte]

#645