Add client-side options support

# Problem
If there are static options passed into the element, the options are deleted on request for filtered options.

# Request
Client-side options should be supported and have filtering available. TBD: Do we allow both client-side (such as default options) *and* server-side options?

# Implementation concerns
## Accessibility
Ensure that any default / client-side options are announced when the input is focused. `screen-reader-announcements.ts` can assist with this.

When the options list isn't visible, an `aria-describedby` should be added to the input pointing to the feedback element. This should only be if the element has client-side options. Remove this `aria-describedby` when the user interacts with any key, and add it back in when the auto-complete-element is blurred. cc @github/accessibility and @jscholes for reference. "aria-live won't cut it" for this scenario

## Developer Notes
There is some initial setup done in `autocomplete.ts` to detect client-side options, but all of this can be removed / reworked, as long as accessibility considerations are met.

Comienza en autocomplete.ts revisando la detección existente de opciones en el cliente y, después, lee screen-reader-announcements.ts para conocer el comportamiento de accesibilidad. Rastrea cómo se eliminan las opciones durante las solicitudes filtradas y define la interacción admitida entre las opciones del cliente y del servidor. Se considera terminado cuando las opciones del cliente siguen disponibles, el filtrado funciona y se cubre el comportamiento descrito de foco, teclado, blur y aria-describedby.

Escrito por el modelo de indexación a partir del texto del issue.