Update `.gitignore`
Update `.gitignore`

* Sort list alphabetically.
* Add `.DS_Store`.
  https://github.com/MicrosoftEdge/Sonar/pull/178#pullrequestreview-36640420

sonarwhal/sonar,alrra/sonar,sonarwhal/sonar,alrra/sonar,alrra/sonar,sonarwhal/sonar