Make auto-spawn support auto-restart

**Is your feature request related to a problem? Please describe.**

If the speech-dispatcher daemon gets auto-spawned from the client library, and crashes, it does not get re-auto-spawned.

**Describe the solution you'd like**
The client library should auto-respawn it.

**Describe alternatives you've considered**
One can also use the systemd socket unit, but better fix auto-spawn too.

Start by tracing the client library's auto-spawn path for the speech-dispatcher daemon and compare it with the systemd socket-unit alternative mentioned in the issue. The work is done when a daemon started by the client is automatically spawned again after it crashes, with the existing auto-spawn behavior preserved.

Written by the indexing model from the issue text.