Feature: fencing: treat remapped reboots as reboots when appropriate

If a topology fencing request has a level with multiple devices, a requested
reboot should be remapped to all-off-then-all-on (consider the case of remote
power switches for redundant power supplies).

This revision ensures that remapped operations are properly treated as
reboots when appropriate: when sending a fencing query, processing query
results, merging incoming fence requests, and reporting fence results to
clients and peers.

Actual remapping is not done yet, so this revision has no effect yet.