Fix files/folders in desktop not opening with right click context menu

UDS_LOCAL_PATH will return the path without file scheme. This schemeless
path will be set in UDS_TARGET_URL and then will be used by kio's
targetUrl and then final passed to Krun where it will fail the scheme test
eventually leading to the said bug.

Fix for this is to create a url using QUrl::fromLocalFile and then
pass the url.toString()'s result to insert.

BUG: 364530
CCMAIL: chinmoyrp65@gmail.com

Differential revision: https://phabricator.kde.org/D2054