Currently the GUI shows confusing error messages when settings.json can't be read or written on startup. This causes the unrecoverable read error described in core#21340 and write error described core#21974.
This PR tries to clarify the error dialog, and adds an option to just clear the settings and reset them to default
Fixes core#21340
Co-authored-by: Jarol Rodriguez <jarolrod@tutanota.com>
This is a backport of core-gui#379