Extended Routing Dashboard

[carlaKC]

The routing dash added in #59 surfaces failure/success rates, channel utilization and resolution time for htlcs that lnd processes.

One thing that's missing from this dash is htlc amounts, which also provide insight into node behaviour. Since the htlc stream is ephemeral, we may want to get this information from forwarding history, rather than our stream. Some things we could surface:

• Bar Graph of amounts (as is done for resolution time)
• Average htlc size (segmented by failure/success)