feat(cli): disable progress bar in CI environment

[matejchalk]

The immediate motivation for this change is to avoid --no-progress argument being used in CI, which is part of an effort to avoid extra CLI arguments which restrict cache reuse in Nx monorepos.

In the future, we'd like to get rid of the progress bar completely and replace it with a spinner. Either way, it would make sense to only show these UI elements when not in running in CI. The --progress argument may be removed in the future though, we'll see. The future improvements are part of a larger effort, see:

• Improve logging and error handling #888

I've created some general purpose utility functions for correctly parsing boolean environment variables, so it now supports conventions like true/false, 1/0, yes/no, on/off, etc. I've reused those for the CP_VERBOSE variable as well.