Add UK business count data visualisation

[luke-strange]

It will live in Purpose & Social Impact as a standalone page for now.

• [x] The data to drive the vis should sit in src/themes/purpose-social-impact/non-profit/_data. flat data file is in working/cs/ukbc_lu.csv
• [x] Will be a hex map by LA, showing the total number of "Non-profit body or mutual association" per Local Authority 2021 district.
• [x] Colour by the total
• [x] Show the top (n) sector name(s) in the tooltip.
• [x] As headlines, we should show the total number of non-profits in the UK, the total in the North, % of Uk business that are non-profit.
• [x] bar chart showing number of each size of company.

[slowe]

We don't have data on the whole of the UK, just The North. So the headlines will have to be limited to the number and percentage of northern businesses that are non-profit.

[slowe]

@luke-strange I think I've done as much as I can for each of the tasks.

[luke-strange]

Thanks, will close this.