Disconnect peers which don't respond to commitment signed after a while #2282
Description
It seems common wisdom in the plebnet crowd is that lnd sometimes just gets stuck and holds onto htlcs and the only way to fix it is disconnect+reconnect to peers. I saw this on two separate channels over the past few days (trying to get debug logs so I can open an lnd issue), including one channel which I ended up force-closing at high fees because the peer hadn't responded to a commitment_signed in days (despite being connected and ping+pong'ing just fine).
Given disconnect+reconnect manages to kick lnd and get it going again, we should probably implement this - if we're in a waiting state for a few blocks and connected, tell the PM to disconnect and let it reconnect eventually.