integrationtest: Collect test results from gnome-desktop-testing-runner

Then the web UI can present this in a useful way.
extras/build.gnome.org: Print (not found) when we don't find a task for a build
build: Show (no components rebuilt) status

It just looks less broken.
build.gnome.org: Rework front page to show current task status

And have a bit more explanation around each task.