sysutils/qtpass: improve port
- install the icon for qtpass
- install qtpass-desktop file
- drop buildtools and linguisttools from the runtime dependencies
- instead of defining a do-install target, fix qtpass.pro to work with the ports system [that change is probably up for debate...].
PR: 204122
Submitted by: Tobias C.Berner <tcberner@gmail.com> (kde)