Globus transfer tracking

[JBorrow]

Track the contents of globus transfers (e.g. average transfer speed) for diagnostics.

1. Create a new table for async transfer diagnostics
2. Write data during the background tasks that check on async transfers
3. Provide information for diagnostics in dashboards

[JBorrow]

Paul and/or James feel free to jump into this one if you have time. We will be doing a database revision anyway for other reasons so we should take the chance of having a breaking change to do this too.