Create benchmarks to measure overhead of this against `println!`

This crate does some stuff on top of just writing to some output. We should write some benchmarks to figure out the performance cost of that.

- Write bechmark to measure time to print _n_ lines of example text (`output.print("lorem ipsum")` vs `println!("lorem ipsum")`)
- [ ] to stdout using the "human" target
- [ ] to stdout using the "human" target's test helper
- [ ] to a file using the "json target
- [ ] print to stdout using `println!`
- [ ] print to stdout using `writeln!` on a locked stdout
- [ ] print to stdout using `writeln!` on a buffered stdout

Start by locating the crate's output.print API, the human and json targets, and any existing benchmark setup. Add measurements for the listed stdout, test-helper, file, println!, locked-stdout, and buffered-stdout cases, and confirm the benchmarks report comparable timings for printing n lines of example text.

Written by the indexing model from the issue text.