This removes `ProcState` and replaces it with a new `CliFactory` which
initializes our "service structs" on demand. This isn't a performance
improvement at the moment for `deno run`, but might unlock performance
improvements in the future.
Creating the node_modules folder when the packages are already
downloaded can take a bit of time and not knowing what is going on can
be confusing. It's better to show a progress bar.
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
