Limit the scope of hook context
Summary: Hook context previously had a bunch of attributes that were not documented, and only used internally. This is due to it implementing an internal-use context, SystemContext. This further limits the scope by removing all of these attributes, and changing callsites accordingly.
Test Plan: unit and lint
Reviewers: alangenfeld, yuhan
Reviewed By: yuhan
Differential Revision: https://dagster.phacility.com/D7462