Accessing GraphQL Context in makeAddPgTableConditionPlugin
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### Summary

I have the need to develop a condition using data from the GraphQL context. It doesn't appear that context is available on 

```
export default function makeAddPgTableConditionPlugin(schemaName: string, tableName: string, conditionFieldName: string, conditionFieldSpecGenerator: (build: Build) => GraphQLInputFieldConfig, conditionGenerator: (value: unknown, helpers: {
    queryBuilder: QueryBuilder;
    sql: typeof sqlType;
    sqlTableAlias: SQL;
}, build: Build) => SQL | null | undefined): Plugin;
```

### Additional context

I'm surprised this isn't talked more about as a use case. There's a wealth of user ad environment information available in `context` for most decent sized APIs and having access to those to build custom condition expressions is pretty crucial. 

Is there any way to access the context from `conditionGenerator`?