chore: add tracing to pty usage (#7127)
### Description
Adding some tracing to our spawning code to measure impact of PTY usage.
Quick tests make it look like the `openpty` call has a minimal impact
(~.2ms) on the time it takes to spawn a process.
<img width="228" alt="Screenshot 2024-01-26 at 10 42 12 AM"
src="https://github.com/vercel/turbo/assets/4131117/fbb11622-7a1d-4638-b733-c6aa12ff1bb2">
<img width="238" alt="Screenshot 2024-01-26 at 10 42 19 AM"
src="https://github.com/vercel/turbo/assets/4131117/b54162ec-7974-40e0-bfb0-4789a45e48c7">
### Testing Instructions
Look at the profiles:
[normal.json](https://github.com/vercel/turbo/files/14068301/normal.json)
[pty.json](https://github.com/vercel/turbo/files/14068303/pty.json)
Closes TURBO-2175
