Closes
https://linear.app/zed-industries/issue/Z-2209/popovers-dont-always-have-syntax-highlighted-code
Closes
https://linear.app/zed-industries/issue/Z-2206/highlight-syntax-in-hover-docs

* Fix a ton of errors in our logs due to us not recognizing that
`elixir-ls` does not support code actions.
* Syntax-highlight elixir code blocks in hover popovers