feat(operations cancel): add new convenience command to cancel an operation

[reubenmiller]

Simple command to update an operation by setting the status to FAILED and using a standard failureReason.

Example

c8y operations list --device 1234 --status EXECUTING | c8y operations cancel

The above command will send the following body to the HTTP request:

{
  "failureReason": "User cancelled operation",
  "status": "FAILED"
}