Fix #20503: implement "Show barlines" setting of "Edit staff types" dlg box.

Bar lines belonging to a single staff are shown/hidden according to the staff type setting.

Bar lines spanning several staves are shown/hidden according to the setting of the staff type of the first spanned staff.

System bar lines (bar lines at the beginning of a system) are NOT hidden, regardless of the setting.
If bar lines are not shown, hide also elements attached to them.
Merge pull request #270 from mgavioli/Fix_#20503_staff_type_ShowBarlines_setting

Fix #20503: implement "Show barlines" setting of "Edit staff types" dlg box