Setup regular unit test runs on buildbot

[KapiX]

I have started cleaning up our test suite. While there is still a significant amount of failures, it would be good to have testing setup already for both gcc2 and x86_64.

This will require Haiku hosts, ideally VMs spun up on demand since the tests can deadlock or KDL the system.

[kallisti5]

Buildbot is now dead.

Haiku now uses concourse. The one down-side of Concourse is the workers are container-based (and Haiku doesn't support runc last I checked)

however if we wanted to start leveraging buildbot for just unit testing i'd be 100% onboard getting that rolled out. Ya gotta write the new config though :-)