Move lsp config to local file structure

.config/nvim/lsp/spyglassmc_language_server.lua

@@ -0,0 +1,24 @@
+---@brief
+---
+--- https://github.com/SpyglassMC/Spyglass/tree/main/packages/language-server
+---
+--- Language server for Minecraft datapacks.
+---
+--- `spyglassmc-language-server` can be installed via `npm`:
+---
+--- ```sh
+--- npm i -g @spyglassmc/language-server
+--- ```
+---
+--- You may also need to configure the filetype:
+---
+--- `autocmd BufNewFile,BufRead *.mcfunction set filetype=mcfunction`
+---
+--- This is automatically done by [CrystalAlpha358/vim-mcfunction](https://github.com/CrystalAlpha358/vim-mcfunction), which also provide syntax highlight.
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'spyglassmc-language-server', '--stdio' },
+  filetypes = { 'mcfunction' },
+  root_markers = { 'pack.mcmeta' },
+}