Move lsp config to local file structure

.config/nvim/lsp/solargraph.lua

@@ -0,0 +1,24 @@
+---@brief
+---
+--- https://solargraph.org/
+---
+--- solargraph, a language server for Ruby
+---
+--- You can install solargraph via gem install.
+---
+--- ```sh
+--- gem install --user-install solargraph
+--- ```
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'solargraph', 'stdio' },
+  settings = {
+    solargraph = {
+      diagnostics = true,
+    },
+  },
+  init_options = { formatting = true },
+  filetypes = { 'ruby' },
+  root_markers = { 'Gemfile', '.git' },
+}