[dagster-graphql] Dagster GraphQL Python Client [2/4]
Summary:
This diff creates the dagster-graphql-client CLI:
- Adds BK checks to ensure that current GraphQL queries by the client are included in a legacy query query_snapshot folder via dagster-graphql-client query check
a. It also adds the `dagster-graphql-client query snapshot` command to add the GraphQL client's queries to the `query_snapshot` directory
- Tests to ensure that each query in the client_backcompat directory is still supported by the GraphQL server (so at a minimum, we can be intentional about breaking changes that arise)
Test Plan: bk script checks + new backcompat tests (this diff is mostly tests)
Differential Revision: https://dagster.phacility.com/D7421