Improve page titles for *past* Scorecards pages

[zarino]

Some pages on the Scorecards site are "evergreen". eg:

Given how social platforms etc might cache the titles of these pages when shared, we don’t want to include the year in these evergreen page titles, so a generic "Council Climate Scorecards" is fine.

But, to avoid confusion when a user is looking at a "past" page (eg: the 2022 Plan Scorecards, or the 2023 Methodology, right now), we want the page <title> to make it clear which Scorecards round you’re looking at. This means:

Path	Current title	New title
/plan-scorecards-2022/	Council Climate Plan Scorecards | Climate Emergency UK	(unchanged)
plan-scorecards-2022/[…]	[…] | Council Climate Scorecards	[…] | Council Climate Plan Scorecards
/2023/methodology/	Methodology | Council Climate Scorecards	Methodology | 2023 Council Climate Scorecards
/	Council Climate Scorecards | Climate Emergency UK	(unchanged)
/methodology/	Methodology | Council Climate Scorecards	(unchanged)
/[…]	[…] | Council Climate Scorecards	(unchanged)

[struan]

Should be able to add the year to the context in middleware and then use this in the templates.