pkg(nixvim): Remove all lang configuration to single file

pkgs/nixvim/lang/lua.nix

@@ -0,0 +1,34 @@
+{
+  lib,
+  pkgs,
+  ...
+}: {
+  lsp.servers.lua_ls = {
+    enable = true;
+  };
+  youthlic.plugins.conform-nvim.settings = {
+    formatters_by_ft.lua = {
+      __unkeyed-1 = "stylua";
+      lsp_format = "fallback";
+    };
+    formatters.stylua = {
+      __raw =
+        #lua
+        ''
+          function()
+              local defaultFormatter = require("conform.formatters.stylua")
+              return vim.tbl_extend("force", defaultFormatter, {
+                command = function()
+                  local exe = vim.fn["exepath"]("stylua")
+                  if exe ~= "" then
+                    return exe
+                  else
+                    return "${lib.getExe pkgs.stylua}"
+                  end
+                end
+              })
+          end
+        '';
+    };
+  };
+}