Clean up coding challenges page

[jdwilkin4]

There is a lot going on with this page and it needs to be updated.

There is a lot of out of date information. And some information that quite frankly can be moved to other specialized guides.

But the goal is to clean this up so new contributors and regular contributors aren't overwhelmed by this page and can instead get the information they need from it.

[majestic-owl448]

You can probably close also #1228 then with the same PR