Restructure of entire RAP for Statistics page, swapping embedded videos to links

Overview of changes

Page has been restructured and edited to hopefully be easier to navigate / read
Callouts modified to Quarto styling
Some Databricks info has been added, although this is still quite minimal
Embedded videos have been removed due to Stream changes, and have been changed to links instead

The page was really long and a bit confusing in the way that it was set up. I've tried to make the sections correspond more closely to the RAP principles, have removed some waffley bits, and have added in some additional info. Hoping this means we can just repeatedly send it out to teams to help them address missing RAP standards and they won't have to dig through extra stuff to find what they need
The long term plan is to change all callouts to Quarto styling so it made sense to fix that whilst editing the page
More and more people will be moving to Databricks so we need to cater to them (still not quite there yet, but it's at least mentioned a bit more)
Videos were broken 😞

[x] I have checked the contributing guidelines
[x] I have checked for and linked any relevant issues that this may resolve
[x] I have checked that these changes build locally
[x] I understand that if merged into main, these changes will be publicly available