Add a flag to the auth command to set the local port

[pacoorozco]

Signed-off-by: pacoorozco [email protected]

What issue type does this pull request address? (keep at least one, remove the others)
/kind enhancement

What is this pull request for? Which issues does it resolve? (use resolves #<issue_number> if possible)
resolves #370

Does this pull request has user-facing changes? (e.g. config changes, new/modified commands, new/modified flags)
Yes, a new flag available in the auth command to set the local port to bind the authentication server.

Does this pull request add new dependencies?
No

What else do we need to know?

[codecov]

Codecov Report

Merging #392 (c359ca2) into main (fc634f1) will decrease coverage by 0.08%.
Report is 1 commits behind head on main.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #392      +/-   ##
==========================================
- Coverage   66.70%   66.62%   -0.08%     
==========================================
  Files          22       22              
  Lines         880      881       +1     
==========================================
  Hits          587      587              
- Misses        270      271       +1     
  Partials       23       23              

Files	Coverage Δ
internal/app/oauth.go	0.00% <0.00%> (ø)

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