fix: require valid project ID for project labels creation

[Sypher845]

Fixes #640

This pull request improves the label creation command in the Harbor CLI by enhancing error handling and adding validation for project-specific labels. The main changes focus on making the command more robust and user-friendly.

Validation for project-specific labels:

• Added a check to ensure that when the label scope is set to project ('p'), a valid ProjectID must be provided. If not, a clear error message is returned.

Result

• Added a check to verify that the specified project exists before creating a project-specific label, returning an error if the project does not exist.

Result

[codecov]

Codecov Report

❌ Patch coverage is 44.44444% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 7.39%. Comparing base (60ad0bd) to head (7d08f42).
⚠️ Report is 82 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/harbor/root/labels/create.go	44.44%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             main    #641      +/-   ##
=========================================
- Coverage   10.99%   7.39%   -3.60%     
=========================================
  Files         173     260      +87     
  Lines        8671   12854    +4183     
=========================================
- Hits          953     951       -2     
- Misses       7612   11794    +4182     
- Partials      106     109       +3     

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[bupd]

/lgtm @Sypher845 please add a test for the changes made. Thanks

[Sypher845]

So sorry, I missed the notification for this! Working on it!!

[Sypher845]

@bupd i have added the tests, please take a look.