This adds support to AnsiTerminal for colored output, and makes all tool output written to stderr (with the printError function) colored red.
No color codes are sent if the terminal doesn't support color (or isn't a terminal).
Also makes "progress" output print the elapsed time when not connected to a terminal, so that redirected output and terminal output match (redirected output doesn't print the spinner, however).
Addresses #17307
Artifacts are now located in a central place.
This will enable us to downlaod artifacts when we need them (instead of
downloading them all upfront).
This also makes replacing sky_snapshot with gen_snapshot easier.
Also, make it clear the screen between results so it's more obvious
what's going on when you have new results (especially when you have
fixed everything).
* add google analytics
* send in the run target type
* track device type targets
* use the real GA code
* review comments
* rev to usage 2.0
* rev to 2.2.0 of usage; add tests
* review comments
