Implement a Rendering Compatibility Test Suite

The idea is that when we add a new syntax it would be nice to be able to quickly run all the tests on that new syntax to verify what works/what doesn't work.

Also having a CTS has several other pros:

• tests are closer to their parser/renderers since they are in the same module
• those tests are unit tests, which means early failures if parser/renderer is broken (incidentally this means higher TPC on nemo too )
• scales better with # of syntaxes
• Allows specific code to handle situation like PDF testing
• know precisely what works and what doesn't since all tests are executed and doesn't depend on the user having added the test or not