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)
2 jobs for master in 84 minutes and 1 second (queued for 103 minutes and 48 seconds)
Status Job ID Name Coverage
  Build
passed #51525
build_clazy_clang_tidy

00:59:36

passed #51524
linux kf5-qt5 qt5.12

00:50:34

36.0%