fix: allow admin users to skip old password input

[adityashekhawat1999]

Description

This updates the user password command to allow admin users to skip entering the old password.

Right now, the CLI always requires the old password but according to the API behaviour it’s optional for admins.

• Fixes [bug]: Password change command only supports system admin #743

Type of Change

Please select the relevant type.

• [ ✅] Bug fix
• New feature
• Refactor
• Documentation update
• Chore / maintenance

Changes

• Added --admin flag to the password command
• Updated validation to allow empty old password when --admin is used

[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 7.81%. Comparing base (60ad0bd) to head (2aa9be1).
⚠️ Report is 118 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/views/password/change/view.go	0.00%	2 Missing ⚠️
cmd/harbor/root/password.go	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             main    #754      +/-   ##
=========================================
- Coverage   10.99%   7.81%   -3.18%     
=========================================
  Files         173     270      +97     
  Lines        8671   13171    +4500     
=========================================
+ Hits          953    1029      +76     
- Misses       7612   12029    +4417     
- Partials      106     113       +7     

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[adityashekhawat1999]

@NucleoFusion The cli would still send the old password field(empty for admin), i wanted to ask is that acceptable for the API or should the field be omitted entirely

[NucleoFusion]

This should be fine, will have a better look.
Lint is failing btw