feat(lsp): switch to official Elixir LSP

lsp/elixir.lua

@@ -1,22 +1,7 @@
 ---@type vim.lsp.Config
---- 'root_dir' is chosen like this:
---- if two or more directories containing `mix.exs` were found when searching
---- directories upward, the second one (higher up) is chosen, with the
---- assumption that it is the root of an umbrella app. Otherwise the directory
---- containing the single mix.exs that was found is chosen.
+--- https://github.com/elixir-lang/expert/blob/main/pages/installation.md#neovim
 return {
-    -- cmd when installing with Mason
-    -- Had to install elixir and asdf (homebrew)
-    -- Then ran `mix local.hex` to upgrade Hex
-    cmd = { vim.env.HOME .. "/.local/share/nvim/mason/packages/elixir-ls/language_server.sh" },
-    -- cmd = { "/Users/oliver.ladner/.local/share/nvim/mason/packages/elixir-ls/language_server.sh" },
     filetypes = { "elixir", "eelixir", "heex", "surface" },
-    root_dir = function(bufnr, on_dir)
-        local fname = vim.api.nvim_buf_get_name(bufnr)
-        local matches = vim.fs.find({ "mix.exs" }, { upward = true, limit = 2, path = fname })
-        local child_or_root_path, maybe_umbrella_path = unpack(matches)
-        local root_dir = vim.fs.dirname(maybe_umbrella_path or child_or_root_path)
-
-        on_dir(root_dir)
-    end,
+    root_markers = { "mix.exs", ".git" },
+    cmd = { "expert" },
 }