Inhibit reboot/shutdown while we're busy copying data to Persistent Storage
Since 5.8, we see a surprisingly high amount of bug reports with corrupted Persistent Storage filesystems, that fails to activate.
The new Persistent Storage implementation copies data to the Persistent Storage somewhat in the background, and if the user reboots at the wrong time, they may end up with a corrupted filesystem.
We could use systemd's inhibit facilities to block reboot/shutdown while tps is busy doing stuff on the Persistent Storage.