FEI supply APY is coming through as 0

[drewcook]

Describe the bug

The supply APY for the FEI asset on Eth mainnet is not coming through from the API. This could either be an API issue or a UI issue. It's worth investigating which.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://app.aave.com/reserve-overview/?underlyingAsset=0x956f47f50a910163d8bf957cf5846d573e7f87ca&marketName=proto_mainnet
2. Observe the 0% APY for supplies

Expected behavior
Should show accurate percentage rates.

[sakulstra]

Some more issues with the rates api:

Only v2 markets supported (half a year after v3 was released)

Stable rate is almost always wrong (should always be analog to variable rate, but higher).

The issue is probably that stable rate on the subgraph is only updated when someone uses it (didn't check, but assume that's what is happening), so https://github.com/aave/aave-api/blob/master/src/services/RatesHistory.ts#L105 will always get the same value.
Should be rather easy to just calculate the stable rate based on the utilization at that point in time.