Feature Request: Upcoming Events Block

### Impacted plugin

Jetpack

### What

Upcoming Events block, similar to the shortcode but with updated features

### How

Could we get an Upcoming Events block, similar to the [shortcode](https://wordpress.com/support/widgets/upcoming-events/#upcoming-events-shortcode) but with more display options?

Minimum lovable product would need:
- A field for the iCAL link
- Formatting options for the date & time (the current shortcode writes out datetimes in a long format, which looks bad when the user needs a more compact list)
- The ability to choose whether to show a Description and Location
- Basic Gutenberg formatting options (fonts, padding, backgrounds, etc)
- The number of events to show
- Nice but not necessary: a link for the user to add the calendar to their device

I think that's it! Happy to offer mockups if they're needed, and if it's helpful, here's how the shortcode displays on a friend's site with and without CSS to hide some stuff to prettify it just a little bit. Users like this kind of feature but what we have doesn't work terribly well for them.

## With some CSS applied to hide location and description fields

## Shortcode as is

Start by reviewing Jetpack’s existing Upcoming Events shortcode and the Gutenberg block entry point. Compare the requested iCAL input, date and time formatting, visibility controls, event count, styling options, and optional device-calendar link with current behavior. Done means an Upcoming Events block supports the minimum lovable product requirements.

Written by the indexing model from the issue text.