Add benchmarks for piped stdout/stderr to a tty

[emberian]

#10558 adds an optimization without a benchmark; try and make a good benchmark for it.

[emberian]

Closing as infeasible. Psuedo-TTYs (ptys) aren't available cross-platform (glares at Windows), and libuv provides no wrapper for them. So the benchmark would require being attached to an actual terminal, which just isn't doable.