Add Endpoints Create & Remove a dependency

[nbcraft]

✨ Add Public Api Create Dependency
✨ Add Public Api Delete Dependency

[salob]

@nbcraft @olegzd I'm getting 404 when trying to use this endpoint

curl -X DELETE -k -H 'X-Authentication-Token: $ZENHUB_TOKEN' -H 'Content-Type: application/json' -i 'https://api.zenhub.com/p1/dependencies' --data '{
  "blocking": {
    "repo_id": 490535397,
    "issue_number": 122
  },
  "blocked": {
    "repo_id": 490535397,
    "issue_number": 123
  }
}'

I don't see an Issues tab not sure where to track this. Thanks!

Monday May 16th - UPDATE - working as normal today! Now correctly getting 204