[schedule/sensor testing 2/n][RFC] fxn to explicitly validate run config
This diff adds a function to validate run config against a pipeline.
I think the point of discussion here will be around what this fxn returns. @sandyryza noted, and I agree, that it would be cool to return something that represents the config after validation (there have been user issues opened regarding this). Should this post-validation config blob just mirror the config blob that we expect passed in? Bc after validation we throw it into EnvironmentConfig, and I don't think we want to make that user-facing.
Will add more unit tests as we tamp down this and surrounding APIs. Will also cross over existing schedule tests in internal to see how it feels in practice.
Reviewers: sandyryza, alangenfeld
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D7944