Create a DiaSource table

[wmwv]

It's become clear that we need a DiaSource table to maintain measurements, flags, and quality about individual detections. sidecar will save to DiaSource table.

1. What does association into DiaObject now look like? When is that triggered and by what agent?
2. What is the schema for DiaSource?
3. What's the relationship between provenance in DiaSource and DiaObject?

[Bharath-Chowdhary-N]

How to integrate ML scores from other sources / teams such as RAPID?