✨feat: Add DeleteContent method for storage

[alperencelik]

This PR aims to add 'DeleteContent' method for storage objects. Here is the relevant API documentation:

https://pve.proxmox.com/pve-docs/api-viewer/index.html#/nodes/{node}/storage/{storage}/content/{volume}

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (fdb95a1) 25.95% compared to head (f910ba6) 25.66%.
Report is 5 commits behind head on main.

Files	Patch %	Lines
storage.go	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #117      +/-   ##
==========================================
- Coverage   25.95%   25.66%   -0.30%     
==========================================
  Files          15       15              
  Lines        1753     1773      +20     
==========================================
  Hits          455      455              
- Misses       1278     1298      +20     
  Partials       20       20              

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[alperencelik]

I've attempted to enhance enabling the deletion of contents by name, as the current deleteVolume() method's private status and dependency on specific content types (iso, vztmpl, and backup) limit this functionality. I would like to hear opinions as well.

[luthermonson]

@alperencelik looks good for now, if we need to do more we can always change it

[alperencelik]

Thank you so much for review @luthermonson!