Add elapsed time for each test in ./mfc.sh test

[sbryngelson]

I'm imagining something like this:

Test pre_process and simulation | from D79C3E6F to 48B9D0C4 (186 tests)

   tests/UUID    Summary

    48CCE072    1D -> bc=-7 | ET: 2.6s
    70DAE9E8    1D -> bc=-4 | ET: 24.5s
    C5B79059    1D -> bc=-9 | ET: 21.3s
    AED93D34    1D -> bc=-8 | ET: 38.3s
    5EC236F2    1D -> bc=-6 | ET: 291.7s
    3AE495F4    1D -> bc=-5 | ET: 12.6s

This would make it easy to tell which tests are eating up testing time on different devices/CIs.