Slideshow Block: Hide navigation buttons when in autoplay mode

#### Describe the solution you'd like

The navigation buttons can become redundant when the Slideshow block is marked to autoplay.

Example: you are a hotel owner and are using the slideshow as a way to present some pictures of the rooms you offer. Those images are purely decoration and there's no need to have a proper navigation system.

An alternative, for now, is to use some CSS:

```
/* Slideshow Block (Autoplay mode): hide the navigation controls */
.wp-block-jetpack-slideshow[data-autoplay=true] .wp-block-jetpack-slideshow_button-prev,
.wp-block-jetpack-slideshow[data-autoplay=true] .wp-block-jetpack-slideshow_button-next,
.wp-block-jetpack-slideshow[data-autoplay=true] .wp-block-jetpack-slideshow_pagination,
.wp-block-jetpack-slideshow[data-autoplay=true] .wp-block-jetpack-slideshow_button-pause {
display: none !important;
}
```
#### Idea
Whenever you check `Autoplay`, we then see the Delay option. The idea is to see some extra features, presented on this mockup:

Thank you!

No source file or test is named; search the Slideshow block for the autoplay setting and the navigation-control selectors shown in the issue. Confirm the requested behavior against the mockup and CSS example: when autoplay is enabled, previous/next, pagination, and pause controls are hidden, while normal mode retains navigation.

Written by the indexing model from the issue text.