SDK support to return the underlying vault's current apy

[jrhea]

The endpoint used for Yearn vaults is:

https://api.yearn.finance/v1/chains/1/vaults/all

It would be nice to have a method that accepts, for example, the token symbol (PT or YT) and returns the vault APY. Something like:

getVaultAPYByTokenSymbol(termAddresses, tokenSymbol)