Feature/map closures hierarchical params v2 (#1982)

* implement hierarchical params across both closure and opaque-ref transformers

* Preserve derive callback destructuring and refresh fixtures

* address cubic review bot's comment pointing out an edge case where unbound identifiers could sometimes be generated

* Normalise identifier fallbacks before reuse

* Preserve optional chaining in captured expressions

* Avoid shadowing captured identifiers when map element param is omitted

Author: mathpirate