feat(cli): add log message for no output in download-output command

[gahyusuh]

What was the problem/requirement? (What/Why)

Currently, if we run download-output command on a job that has no output (for whatever reason), we see the below logs:

Outputs will be downloaded to the following root paths:

> Please enter a number of root path to edit, y to proceed, or n to cancel the download: (y, n) [y]: 1
Error: '1' is not one of 'y', 'n'.
> Please enter a number of root path to edit, y to proceed, or n to cancel the download: (y, n) [y]: y
Outputs will be downloaded to the following root paths:

Downloading Outputs  [------------------------------------]    0%
Download Summary:
    Downloaded 0 files totaling 0.0 B.
    Total download time of 5e-05 seconds at 0.0 B/s.
    Download locations (file counts):

which does not make sense.

What was the solution? (How)

Display an informative message when the download-output command is executed but no output files are available for download.

• In a --output verbose form:

Downloading output from Job "Gahyun's Test Job"
There are no output files available for download at this moment. Please verify that the Job/Step/Task you are trying to download output from has completed successfully.

• In a --output json form:

{"messageType": "title", "value": "Gahyun's Test Job"}
{"messageType": "summary", "value": "There are no output files available for download at this moment. Please verify that the Job/Step/Task you are trying to download output from has completed successfully."}

What is the impact of this change?

improves user experience by providing a clear message

How was this change tested?

• Added a unit test
• Ran hatch run lint && hatch run test and made sure all tests passed.
• Manual end-to-end test a scenario where the output files are not available. Verified that new message displayed correctly.

Was this change documented?

No.

Is this a breaking change?

No.