Cancel privilege operation for read-only target with the current user as owner

Summary:
If the target file (in case of chown, chmod or utime) or parent dir of target
(for other actions) is owned by the user requesting privilege escalation then
it's better to cancel the file operation and ask user to retry after changing
permissions manually.

Reviewers: dfaure, ngraham, elvisangelaccio, #frameworks, #dolphin

Reviewed By: ngraham, #dolphin

Subscribers: kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D14464