Look at adding removedProperties to schema

Should consider `deprecatedProperties` as those which still work but will maybe not one day, where `removedProperties` are a strong declaration that the property is no longer valid for the type.

The issue names no files or tests. Start by locating the existing deprecatedProperties definition and its schema validation or generation entry points, then determine where removedProperties would be represented. Done means the schema clearly distinguishes still-supported deprecated properties from properties declared invalid for the type.

Written by the indexing model from the issue text.