Verify that `npm` is runnable in tests

[avivkeller]

Issues like #52682 and #52884 show that (sometimes) npm is not properly packaged in a release. I believe the tests should also check whether npm works properly to prevent issues like these from occurring.

[targos]

It would be great to have such tests but that won't be easy!

[avivkeller]

It would be great to have such tests but that won't be easy!

I agree that it won't be easy, but IMO this should be a goal.