fix(ocaml): get_language_id (#4327)

## Description
This fixes the error users get from local function `get_language_id`. 

From looking into [nvim-lspconfig
ocamllsp](https://github.com/neovim/nvim-lspconfig/blob/master/lua/lspconfig/server_configurations/ocamllsp.lua)
and other googling around, namely [tjdevries config
files](9b790b90c1/lua/custom/plugins/lsp.lua (L108-L115))
and [another
one](e31c0d61fd/nvim/after/plugin/lspconfig.lua (L67)),
it seems that we can directly set these as filetypes foregoing the
mapping via the additional local function which would also need the
[nvim-lspconfig language_id
mapping](d4814330b2/lua/lspconfig/server_configurations/ocamllsp.lua (L3-L10)).

Please bear in mind I don't do any Ocaml, so it would be great if other
users who do Ocaml could test this PR.
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## Related Issue(s)
Closes #4326
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## Screenshots

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## Checklist

- [x] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

lua/lazyvim/plugins/extras/lang/ocaml.lua

@@ -18,9 +18,14 @@ return {
     opts = {
       servers = {
         ocamllsp = {
-          get_language_id = function(_, ftype)
-            return language_id_of[ftype]
-          end,
+          filetypes = {
+            "ocaml",
+            "ocaml.menhir",
+            "ocaml.interface",
+            "ocaml.ocamllex",
+            "reason",
+            "dune",
+          },
           root_dir = function(fname)
             return require("lspconfig.util").root_pattern(
               "*.opam",