fix(mok): Add KILL capability

This patch hopefully fixes issues with sending kill signals to subprocesses from the master process of dovecot.

Exmaple error logs:
```
Jan 25 00:27:16 master: Error: service(auth): kill(14, SIGINT) failed: Operation not permitted
Jan 25 00:28:16 master: Error: service(auth): Process 14 is ignoring idle SIGINT
```