[HOLD for payment 2023-06-21] Cache node_modules to speed up CI/CD

[roryabraham]

Problem

Our setupNode action runs a lot and often takes 3-5 minutes, which is pretty slow.

Solution

While the actions/setup-node action caches npm / node itself, it doesn't cache the actual node_modules. This means that we're doing a clean install every time, on slow CI machines, and it takes a while. Instead, let's cache the node_modules directory and only run npm ci if needed.

[melvin-bot]

Triggered auto assignment to @zanyrenney (NewFeature), see https://stackoverflowteams.com/c/expensify/questions/14418#:~:text=BugZero%20process%20steps%20for%20feature%20requests for more details.

[roryabraham]

I'm going to handle this one myself @zanyrenney so I'm unassigning you.

[roryabraham]

I've been testing this out over here

[roryabraham]

Got PR ready for review: #20436

[roryabraham]

This is live and seems to work well