* Adding social card infrastructure
* Upgrades doc project to .NET 6
* Adds Playwright
* Changes the console to a web project for Playwright
* Adds social card template
* Added blog content
* Parallelized social image processing
* Updating CI to use .NET 6 for docs build
Fixes some tree rendering problems where lines were not properly drawn
at some levels during some circumstances.
* Change the API back to only allow one root.
* Now uses a stack based approach to rendering instead of recursion.
* Removes the need for measuring the whole tree in advance.
Leave this up to each child to render.
