Versions from package-lock.json are not propagated to output FastBoot package.json

It's possible to end up with incompatible versions of node modules installed in a FastBoot build.

Addon's `package.json`:
```json
{
"dependencies": {
"@example/left-pad": "^1.2.0"
},
"ember-addon": {
"fastbootDependencies": [
"@example/left-pad"
]
}
}
```

`package-lock.json`:
```json
{
"@example/left-pad": "1.2.3"
}
```

... time passes ...

```bash
npm version minor "@example/left-pad"
```

Now it's possible that the `npm install` at build time (using `package-lock.json`) and the `npm install` for a FastBoot required module (`package.json` spit out at build time) end up getting different incompatible versions. These should be tied together.

***

Workaround in our codebase (contains unnecessary code regarding `fastbootDependencies` for this example because our use case also needed to track things included from that top-level module):

```js
// /index.js in an addon.
module.exports = {
included() {
this._super(...arguments);

// FastBoot dependencies must be whitelisted
let moduleName = '@example/left-pad';
let fastbootDependencies = [moduleName];
let version = require(`${moduleName}/package`).version;

// Pin the version to the one at build time.
this.pkg.dependencies[moduleName] = version;
this.pkg['ember-addon'].fastbootDependencies = fastbootDependencies;
}
};
```