feat: use status header on recent Nextcloud versions to detect confirmation error

[susnux]

This is required so that if an API call fails because of e.g. user input error and not because of wrong password the app can handle the error.

E.g. try to create invalid external storage - there is no way to fix it or handle it in the app because the confirmation dialog will never be closed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (b42d001) to head (83be4c5).
⚠️ Report is 21 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1359   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         5    +1     
  Lines           20        30   +10     
  Branches         3         6    +3     
=========================================
+ Hits            20        30   +10     

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