BREAKING(cli/unstable): make ProgressBar writable optional

[timreichen]

This PR removes the ProgressBar writable argument and adds it as an optional property in options with Deno.stderr.writable as the default.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.70%. Comparing base (49512f7) to head (5da8739).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6409      +/-   ##
==========================================
+ Coverage   94.69%   94.70%   +0.01%     
==========================================
  Files         562      562              
  Lines       46648    46646       -2     
  Branches     6569     6569              
==========================================
+ Hits        44172    44175       +3     
+ Misses       2432     2428       -4     
+ Partials       44       43       -1     

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[kt3k]

LGTM