Port AttachmentControllerBase::openWith to ApplicationLauncherJob

Tested with kmail composer, RMB on attachment, OpenWith submenu
(selecting an app, and selecting "Open With" to get the dialog)
1 job for !1 with work/dfaure/port_attachmentcontrollerbase in 42 minutes and 54 seconds (queued for 161 minutes and 49 seconds)
detached
Status Job ID Name Coverage
  Build
passed #51503
linux kf5-qt5 qt5.12

00:42:54

36.0%