[MLv2] Fix template-tags snippet-id (#33902)

* [MLv2] Fix template-tags snippet-id

Looking at this bug I found there were a couple problems that the
converters were not properly handling. First, the conversion to js was
copying snake case to kebab case instead of renaming. Second the conversion to
clojure was not picking up kebab case keys but using the snake case keys.

So I dropped the TemplateTag encoder and decoder and went forward with
js->clj and clj->js since the only tricky part was keeping the tag names
as strings and keeping the :type as keyword.

* Address review comments