capture.output() does not work in non-interactive mode

[gaborcsardi]

We need to use stdout when there is an active sink, I suppose? I am not entirely sure. Reprex:

❯ R -q -e 'capture.output(cli::cli_text("time: {100} year{?s}"))'
> capture.output(cli::cli_text("time: {100} year{?s}"))
time: 100 years
character(0)

[gaborcsardi]

Or rather, the other way. Messages go to stderr by default and we only want to deter them to stdout, if this does not cause any detectable difference.

So that means that if there is a sink for stdout or stderr, then we output to stderr.