Add accesibility links for supported councils

[symroe]

Very rough and ready, I don't really know how React works.

[github-actions]

This PR has been deployed.

• EC widget
• DC widget

[GeoWill]

Well I found your intentional error ;)

I confess the rest is pretty confusing! Not sure how usefully I can review just by reading.
Would it be worth me setting it up locally and try it out?

I'm particularly confused by why the widget wasn't already handling UPRNs, or is it more a case of shuffling the UPRN to where you need it in order to link back to WDIV when there's a split postcode?

[VirginiaDooley]

I had to upgrade several packages and refactor a few things to get this to run. Now that I have (happy to push those changes to another PR if you like), I don't think this change has been added to a sample postcode. If the expectation is to test on live data, I will need an API key.

[symroe]

• Duplicate council ID error fixed
• S3 deployment fixed: this was due to a failing test that I'd not spotted
• Example council ID changed, so AA12AA should now show this link.

I've not added the Welsh translation because I want feedback on what it should say. @pmk01?