Changes a bunch of :doc:`/cmd/*` to :cmd:ref:`*` with the intention of changing it later to something that replicates the previous effect of displaying the commands `short_help`.
Also adds `docs/tests/macro_commands.py` which checks all commands in
`code_examples/macro_commands` against the current yosys build. Format similar
to `run-test.sh` files: logging the file under test and reporting errors.
