We currently fetch the token rates for all tokens (for a given network) in a single call. However, the CoinGecko API we're currently using supports a maximum of 10 token addresses in a single request. Beyond that, it throws an error. The price API that we're considering migrating to has a similar limit of 15 addresses.

We should update the TokenRatesController to batch requests by a configurable amount (10 for now) to avoid hitting this error.