illumos gate

Having written an ad-hoc tool a few different times to do this, I thought it'd be useful to add a wsdiff like tool that uses ctfdump -c to look at the difference between two workspaces for CTF and reports on what's changed between files. While a little simple, this helps give us confidence that changes in the ctf tooling haven't caused changes in the existing gate (or have caused ones that we expect).