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.

test/unit/update.test.ts

@@ -1,4 +1,4 @@
-import * as fs from "fs-extra"
+import { promises as fs } from "fs"
 import * as http from "http"
 import * as path from "path"
 import { SettingsProvider, UpdateSettings } from "../../src/node/settings"
@@ -53,8 +53,8 @@ describe.skip("update", () => {
         host: "localhost",
       })
     })
-    await fs.remove(path.join(tmpdir, "tests/updates"))
-    await fs.mkdirp(path.join(tmpdir, "tests/updates"))
+    await fs.rmdir(path.join(tmpdir, "tests/updates"), { recursive: true })
+    await fs.mkdir(path.join(tmpdir, "tests/updates"), { recursive: true })
   })
 
   afterAll(() => {