Run all the automatable tests

[samth]

These are the tests that look reasonably easy to automate/are already mostly automated.

• Racket tests, file tests fail strangely on docker racket/racket#1870 (maybe fixed?)
• racket/gui tests, Tests expect to be run in a particular directory racket/gui#82
• macro-stepper tests, currently fail on DrDr
• stepper tests, already fixed but not in the release build
• htdp tests, probably same as gui
• distro-build tests, fails with an error,
• redex tests, fails with font rendering issues
• compiler/embed tests, fails with missing collection
• embed-in-c tests, fails with error about -fPIC
• r6rs tests, currently 3 expected failures
• drracket tests, hang in leak-on-run
• framework tests, look complicated and haven't tried yet
• test-engine tests, not sure exactly what the checklist instructions want
• rackunit tests, tests are expected to fail

[jackfirth]

I think the distro-build tests require access to VirtualBox. Automating those to run in an environment-agnostic way on Docker would be very, very difficult.