[Feature Request] Scalars

Hello! 👋

Thanks for an awesome project! I've built a few projects using React and Firebase (Firestore), and lately, I've fallen in love with [scalars](https://graphql.org/learn/schema/#scalar-types). I've actually started building a [library](https://github.com/cobraz/firestore-graphql-scalars) that currently gives you `Timestamp` scalar. This would parse timestamps according to Firestore's package.

I want to bring this to attention for this repository too. Maybe it could be a nice attribution to add scalars into the mix? Scalars are a great way to precise type-safe GraphQL schemas. Personally, I also hope to get some feedback on my library to ensure that it's uniform and attribution to the community.

What do you think? Is scalars something that would fit this project?

The request names GraphQL scalars and Firestore's Timestamp, but no files, tests, or entry points. Start by locating the repository's GraphQL and Firebase/Firestore integration, then clarify which scalar types and public behavior should be supported before defining completion criteria.

Written by the indexing model from the issue text.