Add support for renamePrefix and renamePrefixNamespace closure compiler options

fixed https://github.com/clojure/clojurescript/commit/7a8803ef70cb84c686341353e7ab29928487e388

The option itself is not supported as of now as I'm using the default cljs.closure/set-options function in shadow-cljs. When it is added to CLJS it will become available in shadow-cljs.

I'm currently using the feature internally for the :npm-module target which compiles code so it can be directly consumed by JS tools (or node). I'm setting that manually though so the :rename-prefix-namespace option is not recognized.

Thomas, thanks, I get the same result (no prefix namespace) with a shadow-cljs release build as with cljs (when using the new :rename-prefix-namespace and no :modules)

shadow-cljs.edn

moduleb.cljs

David, thanks, I have attached the updated patch

Ok so they sound like independent options then. Pieter, I'm fine with the patch granted it's updated to augment known-opts.