Consider adding support for data-prevent-double-click="true"

[frankieroberto]

The Design System guidance for buttons says:

If you are working in production and research shows that users are frequently sending information twice, you can configure the button to ignore the second click.

To do this, set the data-prevent-double-click attribute to true.

However it also says:

In the case of slow connections, aim to give the user information about what’s happening, for example, by showing a loading spinner or a modal, before using data-prevent-double-click.

So we shouldn't expect it to be set on every button. Instead, it could be opt-in?

  click_govuk_button("Send", prevent_double_click: true)

cc @peteryates @paulrobertlloyd