4/ Shed RunConfig
We are molting (searching for alternatives to knife emoji, "kill", "rip out", etc.). This removes the ability to set run_id or step_keys_to_execute when invoking execute_pipeline. Note that the GraphQL layer never used this codepath. Adds a convenience method, execute_run, to make the actual codepath clearer.
Test Plan: Unit
Reviewers: alangenfeld, schrockn
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D2809