livereload: Use `X-Forwarded-Host` for Codespace

livereload: Use `X-Forwarded-Host` for Codespace

Codespace has 2 types of usage

1. in browser
2. vscode on local computer

As long as you select 2 (on local), Hugo handles livereload expectedly.
But if you use it in browser, Hugo does not reload on file change, as #9936 said.

This issue happens because `CheckOrigin` always fails.
Remote server could rewrite request host name.
Fix this by respecting `X-Forwarded-Host` header during origin checking

After merging this, you can preview changes lively with codespaece in browser.

```sh
hugo server --liveReloadPort 443
```

Close #9936