Rest API: DELETE /draft/filepath

[francisduvivier]

Currently there is no way yet to remove draft files after you have added them.
This ticket is add that.
Note that this is only needed for draft files because non-draft is considered immutable

[francisduvivier]

Steps

• Add @delete("/apps/{slug}/draft/files/{filePath}") route in private-rest.ts
  • add deleteDraftFile method to BadgeHubData
  • implement in BadgeHubData class by removing the file and updating the database as well.