The audio output is still messed up, but this commit gets everything as
ready as it can get. Fixed up all the testbenches and added state
machines for everything
This module needs way reworked to just be a state machine. I was trying
to get way too tricky with it so I went back to the drawing board and
made a state machine diagram for it. The diagram is included with this
commit. I also moved the current collection of documentation to a doc/
folder, and added a second-long audio rom to test everything out once
the rom_sd is working.
I moved around where packages are. I couldn't find any evidence of where
other people put them, but for now they are in the `lib/` folder. Other
infrastructure changes are that all the weird includes we need to make
the linter happy are gated behind ifdefs, so they don't mess with
vivado.
I kinda can't believe concurrent assertions work because there's so
little info about them, good to ssee they actually do something
