Ensure authentication data is cached properly

Ensure authentication data is cached properly

The attached patch sets the main window on the main directory
lister in DolphinView and KIO jobs in DolphinMainWindow to ensure
that login data for remote protocols such as sftp, ftp are cached
properly for the duration of the application. Otherwise, the end
user is going to end up being unnecessarily re-prompted to enter
password login information.

Thanks to Dawit Alemayehu for the patch!

REVIEW: 104614
FIXED-IN: 4.9.0