Add support for token queries [APE-1244]

[fubuloubu]

Overview

Etherscan's API has a token index that we can use to speedup queries about different tokens

Specification

Once support for https://github.com/ApeWorX/ape-tokens/issues/33 is added, detect if ape_tokens is available (check for ImportError) and import the relevant queries subclasses, then add support for them in the query engine if the classes are used

Dependencies

https://github.com/ApeWorX/ape-tokens/issues/33