Preference page for login related settings [was #14011]
Could allow configuring the following settings:
- saveIdP (default true) -- should IdP be remembered, cf. #13971
- saveSID (default false) -- should SID be saved, default for the checkbox on login screen (#8045)
- allowSaveSID (default true) -- option to not display the save sid box, for public installation etc.?
Might also integrate functionality of the 'Authentication' dialog.