Add comments in setup-build-env/action.yml for where to document prereqs (and the separation between build/run and test).
Add some initial (very basic) text for `test_suites.rst`, listing prereqs and how to run the tests (with subsections for the different optional tests, which is currently docs, functional and unit).
Add sphinx-inline-tabs, use it for tidying up prereq instructions based on OS/platform (mostly helpful in the test suites doc where there are multiple sections split by OS).
Also fixes some single backticks that should be double backtick.
Drop svg badges. Even though they were only appearing in the html version, the latexpdf target was still trying to download them, leading to warnings-as-errors in offline builds.
Drop the parts that are being dropped.
Move the things that are being moved.
Also move the verilog stuff out of README and into the docs.
GettingStarted is less cut and dry, so hold off on that one.
