use npm list instead of custom traversal to get native module versions

[achou11]

Currently not an issue, but somehow had a deps tree locally such that npm list sodium-native looked like this:

└─┬ @comapeo/core@7.1.0
  ├─┬ @hyperswarm/secret-stream@6.9.1
  │ └─┬ sodium-universal@5.0.1
  │   └── sodium-native@5.1.0
  └─┬ sodium-universal@4.0.1
    └── sodium-native@4.3.3

When running npm backend:build, only sodium-native@4.3.3 was detected and built for, which caused runtime errors related to failing to load the library for sodium-native@5.1.0. I've since updated locally such that it now looks like this, which works with the existing implementation:

└─┬ @comapeo/core@7.1.0
  ├─┬ @hyperswarm/secret-stream@6.9.1
  │ ├─┬ noise-curve-ed@2.1.0
  │ │ └─┬ sodium-universal@5.0.1
  │ │   └── sodium-native@5.1.0
  │ ├─┬ noise-handshake@4.2.0
  │ │ └─┬ sodium-universal@5.0.1
  │ │   └── sodium-native@5.1.0
  │ ├─┬ sodium-secretstream@1.2.0
  │ │ └─┬ sodium-universal@5.0.1
  │ │   └── sodium-native@5.1.0
  │ └─┬ sodium-universal@5.0.1
  │   └── sodium-native@5.1.0
  └─┬ sodium-universal@4.0.1
    └── sodium-native@4.3.3

The custom fs traversal for finding versions most likely doesn't account for the "extra" layer seen with sodium-universal in the failing example. Instead of updating the existing implementation, I think it'd be safer to use npm directly via its ls command (docs). Passing the --parseable flag causes the stdout to be a newline-separated list of absolute paths to the module e.g.

❯ npm list sodium-native --parseable
/<redacted>/backend/node_modules/sodium-native
/<redacted>/backend/node_modules/@hyperswarm/secret-stream/node_modules/sodium-native
/<redacted>/backend/node_modules/noise-curve-ed/node_modules/sodium-native
/<redacted>/backend/node_modules/noise-handshake/node_modules/sodium-native
/<redacted>/backend/node_modules/sodium-secretstream/node_modules/sodium-native

From an eye test, this approach is slightly slower than the existing approach but is less prone to error.

[gmaclennan]

Added 835f46a just because spawning an npm ls for every module seems a lot, and we can also skip the package.json lookup. 3.27s --> 0.57s on my machine.