[kio] Mount device during stat if necessary
The devices are mounted during the listDir stage in the KIO slave. However, there can be situations where Dolphin already "knows" about the dir content and thus does not call listDir. If in that state the device isn't actually mounted and the user tries to browse it it will result in an error saying that a folder was not found.
To reproduce: Start Dolphin Start kdeconnectd Browse device, listDir gets called killall kdeconnectd Start kdeconnectd Browse device, listDir doesn't get called, but stat is ERROR
To solve this we can check whether the device is actually mounted during stat() and mount if needed.