This changes the assertion error here from:
"AssertionError: 10 != 5" in "test.assertEqual(process.GetState(), lldb.eStateStopped)"
to something like:
AssertionError: Test process is not stopped at breakpoint, but instead in state 'exited'. Exit code/status: -1. Exit description: killed or interrupted while attaching. stderr of inferior: some stuff that the test process printed
Also made the State->String conversion function print the enum integer value when failing a test to make this
easier to debug in case something goes wrong.