[FR] Include raw HTTPS responses in errors

**Is your feature request related to a problem? Please describe.**
I am converting APNs tokens to Firebase registration tokens ("FRTs") on-the-fly in a backend push service. Many converted FRTs fail with the error `messaging/invalid-argument`, with no clues of what's going on. Through some fairly time consuming debugging using the Google API Explorer I was able to get some more details on what was happening, but it's a frustrating process.

**Describe the solution you'd like**
Provide the raw HTTPS response in the thrown `FirebaseMessagingError`. The python SDK [has this](https://firebase.google.com/docs/reference/admin/python/firebase_admin.exceptions), so I think it makes sense that the Node one would too. It would be especially helpful in cases like this where the error code doesn't make much sense.

**Describe alternatives you've considered**
The only real option to attain more info would be to use the REST API directly, but that feels a little over the top.

**Additional context**
There's definitely a possibility that the server or app is misconfigured somehow. Fixing the error is not the point here, though!