Add examples and tests for translating error message and summary list content

[vanitabarrett]

The error message and summary list have hardcoded content order with visually hidden text which makes them difficult to translate. For our MVP internationalisation implementation, we're going to recommend users set this visually hidden text to false and then pass their own translations through the html macro option (this is already possible with the current macro options).

We should make sure we have some examples and tests for this in our review app, so we can make sure we don't unintentionally break this when making any future changes to the components.

Who needs to work on this

Developers

Who needs to review this

Developers

Done when

• Error message component has an example of translating the visually hidden text in the review app
• Error message component has a test for translating the visually hidden text
• Summary list component has an example of translating the visually hidden text in the review app
• Summary list component has a test for translating the visually hidden text