[RFC] dagster-graphql --remote HOST

Summary: Add the ability for dagster-graphql CLI to target a remote dagit server and execute GraphQL against it.

Test Plan:

$ dagster-graphql -r http://localhost:3333 -t {__typename}
{'data': {'__typename': 'Query'}}

Reviewers: #ft, natekupp

Reviewed By: #ft, natekupp

Subscribers: natekupp

Differential Revision: https://dagster.phacility.com/D1263