Scan blockchain for failed storage obligations for host scoring

[ChrisSchinnerl]

We could do something like count the number of successful and failed storage obligations for each host and keep a count for each host. That could be an indicator for how much data a host has lost historically.

[ChrisSchinnerl]

Moving this back to backlog for now since we can only implement it for V2FileContractElement anyway since the v1 type doesn't provide easy access to the host key.