1. Rewrites the tests to be more back and forth rather than getting the
output all at once (which I believe was causing the hangs on linux and
maybe mac)
2. Runs the pty tests on the linux ci.
3. Fixes a bunch of tests that were just wrong.
4. Adds timeouts on the pty tests.
This is a super basic initial implementation. We don't create a
`node_modules/.bin` folder at the moment and add it to the PATH like we
should which is necessary to make command name resolution in the
subprocess work properly (ex. you run a script that launches another
script that then tries to launch an "npx command"... this won't work
atm).
Closes #17492
