Merge: make nitunit more colorful (and useful?)

This series move more information in the UnitTest class, this allow specific and unified way of displaying the test results.

See the asciinema: https://asciinema.org/a/108jd2a3tkfifg3wzoacg0a65

Comments? Needs? Ideas?

Pull-Request: #2121
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>