GR: Add npm lockfile read tests (#853)

Added tests for reading package-lock.json into deps.dev graphs.
I set up the test data by publishing packages to a local private
registry, so the lockfiles/graphs aren't massive.

I'm trying to work out a way to mock the npm registry before I do the
lockfile writing tests.

Author: michaelkedar

internal/resolution/lockfile/fixtures/npm_v1/package-lock.json

@@ -0,0 +1,18 @@
+{
+  "name": "r",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "@fake-registry/a": "^1.2.3",
+    "@fake-registry/b": "^1.0.1"
+  },
+  "devDependencies": {
+    "a-dev": "npm:@fake-registry/a@^2.3.4"
+  }
+}