LicenseService: Track paused/dead client connections

As a customer or Qt Company
I want that if a user suspends the license consuming client sessions
The License Service is able to detect this
So that we can release the ongoing floating license reservations automatically and to prevent the floating license overuse.

The user may CTRL+Z or suspend the client by other means. Also we may end up having zombie processes at least on Linux/macOS. In these cases it would be useful if the daemon can detect this and release the floating licenses which are overdue.

The License Service could track the (current) heart-beats of each client connection and check if the heart beats have not been received in expected time frame (maybe allow some leeway here). If the client is assumed paused/dead we can force release the (floating) license reservation automatically. We probably need to kill the client socket connection too.

Note: The admin of the on-premises instance already has the option to force release current reservations, but this option is not per user, it's per license number only.