[WEB-4688] Add UI basis for redesigned footer component

[jamiehenson]

This PR adds the basis for the redesigned footer component that forms part of the wider navigation rewrite. However, due to misalignment, this PR isn't the whole story - we're missing the full feedback-reporting functionality (though the UI for it is here), and the 'last updated' field is driven by frontmatter (currently a new field and therefore unpopulated) instead of an existing data source.

I will return to the feedback functionality once there's further clarity on it, but I may as well push forwards on the UI.

To test, go on the review app and look around, ensuring it works well at different viewports. This is a pretty surface level change so doesn't require deep testing.

For completeness, here's a snap of the feedback form when enabled:

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch web-4688-footer

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[aralovelace]

How did you enable the Edit on Github? cant seem to see that on my page

Also if the page is too wide is this the expected?

[jamiehenson]

Woops @aralovelace you shouldn't see the feedback unit - it's supposed to be hidden in this PR as the wider purpose of it is still undecided. I toggled it on to take a screenshot and accidentally committed it. Updated that now.

As for the "Edit on Github" bit, it's situational, you'll only get it on the (I guess you could call them) standard docs pages like this. You won't get it on the homepage for instance as we don't want to invite people to edit that on Github. There could be a "last updated" field as well, but that data isn't actually available anywhere atm.

As for the wideness, it's a good point - this is part of some Jamie W feedback as well and will be addressed once all these base pieces are in place.

[aralovelace]

Yes, I dont see it anymore now

and overlooks good