Refactor GrantPermissionOptions parsing to mapping

- Turns GrantPermissionsOptions to a value type from a pointer as this
  type is not need to be used to be mutated.
- Moves Sobek transformation to the mapping layer.
- Errors out if an incorrect option is given. This way we don't surprise
  users and train them to use the API correctly. Otherwise, hiding these
  errors might lead to unexpected issues.