Add option to create clojure file (namespace)

**Is your feature request related to a problem? Please describe.**
When need to create a new clojure file it does not have the proper action, so need to create a generic file with `clj` extension. This could lead to errors while using `-` instead of `_` on file names. 

**Describe the solution you'd like**
Have a dedicated action to create clojure files (namespace) with proper validation on name. 