Unable to get manifest.json file behind Basic Auth

**Describe the bug**
When running `bubblewrap init --manifest`, if the file is behind Basic Auth, the command just crashes. It doesn't ask for credentials or try to parse them from the url if they're passed on it. We are trying to generate an apk for an internal site, which is why it's not publicly available.

The error is `cli ERROR Unexpected token < in JSON at position 0`, which means it's trying to parse the 401 response HTML

**To Reproduce**
Steps to reproduce the behavior:
1. Just run the command `bubblewrap init --manifest https://jigsaw.w3.org/HTTP/Basic/` (doesn't have an actual manifest.json file behind the auth but it doesn't matter for this)

**Expected behavior**
The utility asks for the credentials, or accepts them in the format https://username:password@[host]

**Screenshots**
Not needed I think

**Desktop (please complete the following information):**
Doesn't matter

**Smartphone (please complete the following information):**
Doesn't matter