Function add_enum_def 

fn add_enum_def(
    edit: &mut SourceChangeBuilder,
    ctx: &AssistContext<'_, '_>,
    usages: &UsageSearchResult,
    target_node: SyntaxNode,
    target_module: &Module,
    make: &SyntaxFactory,
) -> Option<()>

Adds the definition of the new enum before the target node.