[SPIKE] Check for broken external links

[colinrotherham]

Quick spike PR to review broken link output for external links too

We currently use hyperlink --internal and have missed quite a few

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[stevenjmesser]

Can you add a description (on here and the linked issue) for what this does and any processes that would need to be created or changed as a result? Should help with giving a fuller review, rather than just a technical review. Ta!

[colinrotherham]

Can you add a description (on here and the linked issue) for what this does and any processes that would need to be created or changed as a result? Should help with giving a fuller review, rather than just a technical review. Ta!

@stevenjmesser No review required for this one, just wanting to look at the broken link check output

[owenatgov]

Given this was a quick spike, I'm gonna close this. However I think this would be useful as something we run every now and then I'll make a searate PR to address the external links found in spike.