Reorganise the dev docs linking to new JS tooling

Once the new JS infrastructure is in place we need to make sure that all the beautiful documentation which has been created is moved front and centre in the dev wiki and structured well so that developers know how to do things in the brave new world.

We should also:
A) remove all outdated JS docs
B) update the remaining ones to list old and new ways of doing things

Note: we should be careful to provide some information for people developing on legacy versions.