add dry-run support for publish command

[glours]

What I did
Add --dry-run support to alpha publish command to avoid pushing artifacts to the registry

Related issue
Issue reported by a Docker Captain during DockerCon

(not mandatory) A picture of a cute animal, if possible in relation to what you did

[codecov]

Codecov Report

Attention: 34 lines in your changes are missing coverage. Please review.

Comparison is base (a345515) 57.55% compared to head (dc49396) 57.48%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11067      +/-   ##
==========================================
- Coverage   57.55%   57.48%   -0.07%     
==========================================
  Files         129      129              
  Lines       11237    11239       +2     
==========================================
- Hits         6467     6461       -6     
- Misses       4141     4147       +6     
- Partials      629      631       +2     

Files	Coverage Δ
pkg/compose/publish.go	0.00% <0.00%> (ø)

... and 3 files with indirect coverage changes

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[jkoenig134]

Hehe, that captain was me messing around with the new publish feature. Great that you found the error!