Move lsp config to local file structure

.config/nvim/lsp/ruby_lsp.lua

@@ -0,0 +1,27 @@
+---@brief
+---
+--- https://shopify.github.io/ruby-lsp/
+---
+--- This gem is an implementation of the language server protocol specification for
+--- Ruby, used to improve editor features.
+---
+--- Install the gem. There's no need to require it, since the server is used as a
+--- standalone executable.
+---
+--- ```sh
+--- gem install ruby-lsp
+--- ```
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'ruby-lsp' },
+  filetypes = { 'ruby', 'eruby' },
+  root_markers = { 'Gemfile', '.git' },
+  init_options = {
+    formatter = 'auto',
+  },
+  reuse_client = function(client, config)
+    config.cmd_cwd = config.root_dir
+    return client.config.cmd_cwd == config.cmd_cwd
+  end,
+}