Move lsp config to local file structure

.config/nvim/lsp/reason_ls.lua

@@ -0,0 +1,12 @@
+---@brief
+---
+--- Reason language server
+---
+--- You can install reason language server from [reason-language-server](https://github.com/jaredly/reason-language-server) repository.
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'reason-language-server' },
+  filetypes = { 'reason' },
+  root_markers = { 'bsconfig.json', '.git' },
+}