Optimize VA-Spec Object Creation

[bencap]

VA-Spec object creation can take upwards of a minute and a half for score sets with large numbers of variants, and we should seek ways that might improve the response time of endpoints creating variant annotation objects. Although the size of the response is large, the main areas for savings are likely to be:

• The creation of each VA-Spec object (we loop individually through each mapped variant to create the objects)
• The serialization and validation of Pydantic objects in the response (we must validate each object in the response list)

We might consider:

• Paginating responses
• Streaming responses
• Limiting the use of Pydantic:
  • Deferring the creation of VA-Spec objects until the response, or
  • Modeling the response as a simpler data structure to limit validation upon returning models
• Processing jobs in the background (probably not worth it)
• Adding better timing metrics to these functions