better graphql query detection & hashing

graphql queries

- are `application/json`
- have a `operationName` property
- have a `variables` property

`operationName` & `variables` can be used for hashing, or generating a human-readable file names

- [ ] switch to human-readable file names
  - [ ] query string & hash as file names if they exist
  - [ ] graphql queries: `operationName` & `variables` as file names