Add neocaml-mode support to ocamlformat-before-save neocaml (https://github.com/bbatsov/neocaml) is a new tree-sitter based OCaml major mode for Emacs. Add `neocaml-mode` and `neocaml-interface-mode` to the mode whitelist in `ocamlformat-before-save` so format-on-save works in neocaml buffers.