Resolve Versions fix
Summary: If the original io_manager resource key is not in use, and a user provides an additional key for an io manager, the default io_manager key will still have a config entry. This breaks an old invariant in the version resolution code path. Removed this outdated invariant and added a test to ensure correct behavior.
Test Plan: unit
Reviewers: sandyryza, alangenfeld
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D8306