Problem

We want to use only lowercase addresses in our GraphQL schemas for two reasons:

1. The Graph only works with lowercase (backward-compatibility)
2. Having lowercase is better, anyway, since it creates a standard and the UI can know for sure that the data fed by the GraphQL endpoint is always formatted like this.

The problem is that Envio passes checksummed addresses, and this results into issues like this:

cc @gavriliumircea

Solution

Provide a new top-level field in the YAML config that lets developers choose their preference for lowercase-only EVM addresses.

That is, all event parameters indexed through Envio would be passed as lowercase, so that don't have to call toLowerCase() manually in our mappings.