Shared CLJ/CLJS lib (#14980)

* Shared CLJ/CLJS lib (PoC/WIP)

* PoC 2.0

* Fixes 

* More test fixes 

* Bump shadow-cljs version

* Fix more stuff

* Need to ^:export the exports

* CI fixes 

* Add eslintignore

* Ignore cljs files for FE code coverage

* Try prefixing CLJS -> JS import with goog:

* Revert indentation change

* No goog:

* Add .prettierignore

* Use advanced build for now for JS tests unit we can figure out how to make it work