Make it easier to refer `instaparse.core/defparser` from modern ClojureScript

[sumbach]

• As of ClojureScript 1.9.198, a .cljs namespace can expose macros from the corresponding .clj namespace; consumers of the .cljs namespace address vars (from the .cljs ns) and macros (from the .clj ns) without additional :require-macros/:include-macros/:refer-macros:
  • https://clojure.atlassian.net/browse/CLJS-1507
  • https://clojurescript.org/guides/ns-forms#_implicit_sugar
• Since this is a .cljc file, we need to use a reader conditional:
  • https://code.thheller.com/blog/shadow-cljs/2019/10/12/clojurescript-macros.html#gotcha-5-cljc