[dagster-graphql-client] Allow HTTPS use
After a lot of back and forth, we were able to finally sort out this issue as related to using http vs. https.
Therefore, adding a flag that allows users to specify whether or not they want to use HTTPS in the client's connection URL.
Test Plan: bk
Reviewers: dgibson, owen
Reviewed By: dgibson
Differential Revision: https://dagster.phacility.com/D8320