advanced: support JSON keys

[Orta Therox]

Could determine if a JSON key has changed, and if so run a script:

  "pull-lock": {
    "package.json@prettier": "echo "Restarting VS Code due to prettier updates; kill code",
  }

Would fix a bunch of bugs we've had this week artsy/emission#910 (comment) artsy/emission#903 (comment)