Improve tooltip of the QAxSelect dialog

- Add the root key.
- Expand all environment variables.
- Add a type enumeration for in/out of process controls.
- Mark non-existent binaries red.

Change-Id: I5671ea0d6f8e2fee1ca8da586e393e04efff5860
Reviewed-by: Andy Shaw <andy.shaw@qt.io>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>