Replace fs-extra with fs.promises

Remove the Mac directory copy instead of refactoring it since we've had
this for a long time now and I think it's safe to assume that users
running code-server on Mac don't have the old directory anymore.

src/node/settings.ts

@@ -1,6 +1,6 @@
 import { logger } from "@coder/logger"
 import { Query } from "express-serve-static-core"
-import * as fs from "fs-extra"
+import { promises as fs } from "fs"
 import * as path from "path"
 import { paths } from "./util"