Add cannot_start_yet argument to the task list status component

[peteryates]

It provides a nicer way to add the class govuk-task-list__status--cannot-start-yet than manually providing it.

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[frankieroberto]

Nice! Wonder if we should throw an error if this is set to true and an href is present?

[peteryates]

That sounds sensible to me. I don't think there's ever a reason for a row to be 'cannot start' and have a href 🤔

I guess a warning message in the log could work too if we want to give some degree of flexibility.

[frankieroberto]

I think I would go with raising an error as warnings in the logs can be missed or ignored - the error could also suggest that if you really wanted to do it, you could add the class manually?

(We could also drop the error in future if someone explains a good reason to have a link for something that can’t be started yet?)