Add timing information to ucm commands

[matthughes]

Is your feature request related to a problem? Please describe. Would like to be able to report how long a ucm command (compile, run, etc) takes

Describe the solution you'd like A new flag --timings to ucm or a timings.on/timings.off commands

Describe alternatives you've considered Looking at my watch

Additional context I experienced unusual compilation times and wanted to report it. I wanted to be able to do so with precision but had to rely on my own counting.

[ceedubs]

I tend to run ucm with UNISON_DEBUG=timing ucm and that prints out some timings. But perhaps not for everything that you would want.