Aave: Add additional lending_reserve stats to schema

[kenkunz]

Goal

As an investor or strategy developer, I want to filter and sort by additional lending_protocol stats and see these data points displayed on search results.

Details

See:

• tradingstrategy-ai/oracle#329
• tradingstrategy-ai/oracle#417
• tradingstrategy-ai/oracle#418

The stats that would be most valuable are: total_supply, total_borrowed. These should both be indexed so they can be used for filtering and sorting.

We should consider updating the schema to make use of the new-ish nested objects feature. We could nest all lending_reserve data under a lending_reserve object (and move some other properties under a more appropriate parent object).