Add error summary box component

[gabwhite]

On long pages (such as a "review your application" page), there might be multiple errors. An "error summary" similar to this gds version will let users know where they went wrong after trying to submit/advance to next step

[connorscarolyns]

The consensus is, the error summary is a better approach than the button error. Let's move forward with creating a new component for the error summary, based on the UK component, and reshape the button error content to reflect the summary error as the best approach.

https://design-system.service.gov.uk/components/error-summary/