## Description 

* Adds snapshot tests to ensure schema stability

* Adds command to dump the schema

```
$  ./target/debug/sui-graphql-rpc generate-schema

type Query {
        chainIdentifier: String!
}


schema {
        query: Query
}

```

## Test Plan 

Manual

---
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### Type of Change (Check all that apply)

- [ ] protocol change
- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes