Add several missing ASTNode macro methods

[HertzDevil]

Adds:

• Annotation#name
  • Add argless #annotations overload #9326 converts the name to a MacroId on behalf of the user. This PR returns the Path directly (like Generic).
• {Case,When}#exhaustive?
• Call#global?
• Def#{abstract?,free_vars}

The rationale is due to #3274 (comment).

Annotations are constituents of defs, but annotation nodes are not constituents of def nodes, so this does not implement #9322.