GPX Demo

DRAFT GPX File Map Component  - not for public use

This is a demo of a new container template (#234237) that could be a candidate for all or part of a future NPDS component.

It uses leaflet.js to read a local GPX file (remote ones should be possible too but may introduce CORS issues) and auto-fit the route and centre to the page.  The GPX file simply needs to be uploaded somewhere in Matrix (child asset of the embedding page seems the most obvious place, but we may want to restrict who can do this following a risk assessment e.g. incorrect or out of date routes being uploaded and resulting in injuries).  Also needs reviewing for accessibility before publishing further.