Improved auto rescue routine

[jkilpatr]

Right now the auto rescue code located here

1. does not reboot the router if it can still ping out even if it's nonfunctional at general routing
2. sometimes crashes and then the router is unable to rescue itself at a later time.

Changes

• implement an auto restart to the rescue loop, like we see in other rita loops
• detect if our own wg_exit tunnel has a stale handshake, as it's a good indications something is very wrong
• Trying to optimize how many tunnels we iterate over/check is probably a bad idea, we should probably just loop over them all. One stale tunnel is a sign tunnel cleanup is dead, many stale tunnels is a sign of complete failure.