Implement the ability to use .focus() on focusable input/select components.

[kiley-mitti]

The Astro docs (and code) have a setFocus() method for several components, including rux-select and rux-input.

While this does appear to work, still, we may be able to take advantage of the shadowRoot's delegatesFocus option to allow users to use the native .focus() method and achieve the same thing.

If possible, this would resolve a small papercut in using components, where developers need to know about the .setFocus() method and use it rather than the more common .focus() method.

Thanks to @nortonprojects for the suggestion!