R1:2ef5b5321d1f

Move Drydock logs to PHIDs and increased structure

Summary:
Ref T9252. Several general changes here:

- Moves logs to use PHIDs instead of IDs. This generally improves flexibility (for example, it's a lot easier to render handles).
- Adds `blueprintPHID` to logs. Although you can usually figure this out from the leasePHID or resourcePHID, it lets us query relevant logs on Blueprint views.
- Instead of making logs a top-level object, make them strictly a sub-object of Blueprints, Resources and Leases.