Manage resource deletion and event filtering, fix imports

[phlg]

• Adds three flags to toggle resource deletion on the S3 backend. Caveats :
  • Bucket deletion will fail if not empty
  • Path deletion only removes the .keep file, not everything matching the path as a prefix
  • The account used to run the operator must have the necessary rights (s3:DeleteBucket, s3:DeleteObject, admin:DeletePolicy)
• Changes the event filtering logic, see comments in any of the controller for details
• Fix the imports incorrectly referencing a fork under my personal GH namespace