Support full paths for failed test locations

[JosephTLyons]

At the moment, when a test fails, I need to copy and paste the test's name that failed into project search to get to it. It would be really great if for failed tests, startest could output the exact path to the failed test, so we could cmd+click on them in our editor's terminal and jump straight to the failing test in the source, similar to cargo test:

thread 'tests::it_works' panicked at src/lib.rs:12:9:
                                     ^^^^^^^^^^^^^^^
assertion `left == right` failed
  left: 5
 right: 4
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace