Add support for LXC clone

[alperencelik]

Hi,

I'm currently working on a Kubernetes operator for Proxmox and am impressed by the "go-proxmox" project. I realized that cloning an LXC is not implemented by the client so my PR tries to have an implementation of LXC cloning.

Here is the relevant API documentation on Proxmox:

[alperencelik]

Thanks for the prompt response. I tried to cover things that you mentioned so it might require another review.

[luthermonson]

good work!

[codecov]

Codecov Report

Merging #99 (4affbb8) into main (b660812) will increase coverage by 0.05%.
Report is 3 commits behind head on main.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main      #99      +/-   ##
==========================================
+ Coverage   26.10%   26.16%   +0.05%     
==========================================
  Files          15       15              
  Lines        1712     1739      +27     
==========================================
+ Hits          447      455       +8     
- Misses       1245     1264      +19     
  Partials       20       20              

Files	Coverage Δ
types.go	57.71% <ø> (ø)
containers.go	0.00% <0.00%> (ø)

... and 2 files with indirect coverage changes

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