Add feedback message for API responses with HTTP 204 No Content in CLI commands

[rosanch]

Related command
az acr private-endpoint-connection delete -r myRegistry -n anyValue

Is your feature request related to a problem? Please describe.
When the API returns an HTTP 204 No Content status code, the lack of any output can be misleading to the user. It may give the impression that the resource was successfully deleted, even though no resource was actually affected. This is particularly confusing when 204 is used instead of a more intuitive 404 for non-existent resources.

Describe the solution you'd like
Print a warning in such cases, such as "Warning: No content" or "Warning: No resource was deleted." This would help clarify to the user that the command did not perform any deletion, even though the API response was not an error.

Describe alternatives you've considered
The only alternative would be if ARM enforced the use of 404 instead of 204 in these scenarios, which is outside the CLI's scope of control. A client-side message remains the most practical solution.

Additional context
This issue is not limited to this specific command; it can impact any command interacting with APIs that return 204 status codes.

[yonzhan]

Thank you for opening this issue, we will look into it.

[toddysm]

@getk12 We should consider better handling of such responses for usability.

[johnsonshi]

@FeynmanZhou you can also include this as a follow up to the delete experiences revamp that you are working on. As reported by the customer, today, running az acr <xxx> delete on a non-existent resource causes (1) 204 no content to be returned (instead of the expected 404 not found), and (2) no output is shown. We should revamp this experience after your fundamentals work.