Rationalise URLs

[microbit-matt-hillsdon]

The previous scheme assumed that we'd maintain independent state for the tabs, but we decided against that.
Therefore we can go for a more traditional URL routing scheme.
It could do with some simplification but, if we can fix the animation issue then exposing these URLs would be a step forward.

[github-actions]

Preview build will be at
https://review-python-editor-next.microbit.org/url-tidy/

[microbit-matt-hillsdon]

Discussed having /reference/display/scroll and similarly for API.

Ideally we'd decorate the data so that each reference topic and API entry knew its full slug and then keep the navigation logic largely the same.

[microbit-matt-hillsdon]

Discussed having /reference/display/scroll and similarly for API.

Ideally we'd decorate the data so that each reference topic and API entry knew its full slug and then keep the navigation logic largely the same.

I gave this some thought. This is a lot of change for a relatively minor benefit. I think we'd change the CMS model if we considered this goal up front. The slugs as used are unique, just not qualified by module (for Reference) and I think they'll be OK in practice.

[microbit-robert]

LGTM.