Clean up FileTransferJob description

* Set magic `destUrl` property to let it know the job destination in case of
  multiple files being transferred
* Set a normal "Receiving File(s)" title like we do with "Copying" title
* Set device name and destination path as details
1 job for master in 5 minutes and 37 seconds (queued for 52 minutes and 12 seconds)
Status Job ID Name Coverage
passed #89658
linux kf5-qt5 qt5.15