It can sometimes be difficult to tell from the debug.log and test stdout
which test was the last to run before the test runner hangs or exits the
QEMU instance unexpectedly.
Print out a start message before each test is executed, along with a
progress message indicating which test out of how many tests we're about
to run.
If a test run has a lot of tests in it, and they fill up the terminal
buffer, it can be difficult to find out exactly which tests have failed
from your large test run. Make TestRunner print out an optional Vector
of failed test names at the end of the run, and have run-tests add each
failed or crashed test to a Vector it uses for this purpose.
Split out the functionality to gather multiple tests from the filesystem
and run them in turn into Test::TestRunner, and leave the JavaScript
specific test harness logic in Test::JS::TestRunner and friends.
