Add nvim-lazy submodule and add plugin configuration.

pkgsets/nvim/lsp/lua.nix

@@ -0,0 +1,26 @@
+{
+  lib,
+  config,
+  pkgs,
+  ...
+}:
+
+lib.optionalString (lib.elem "nvim::lsp::lua" config.machine.pkgs) # lua
+  ''
+    lspconfig.lua_ls.setup({
+      cmd = {"${pkgs.lua-language-server}/bin/lua-language-server"},
+      settings = {
+        Lua = {
+          runtime = {
+            version = 'LuaJIT'
+          },
+          workspace = {
+            checkThirdParty = false,
+            library = {
+                vim.env.VIMRUNTIME
+            }
+          }
+        }
+      }
+    })
+  ''