Controller: allow overriding value of binary flags

[geonnave]

Allows passing e.g. --no-webbrowser and override a webbrowser = true config from a toml config file.
Doing that was not possible with click's is_flag=True.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.84%. Comparing base (7883c03) to head (24f313d).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #211   +/-   ##
=======================================
  Coverage   68.84%   68.84%           
=======================================
  Files          40       40           
  Lines        3739     3739           
=======================================
  Hits         2574     2574           
  Misses       1165     1165           

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[aabadie]

Can you fix the broken test?