FR: group changelog commits by type and scope

**Is your feature request related to a problem? Please describe.**
There is currently a way to group commits into changelog sections by the type of the commit, but not the scope.
**Describe the solution you'd like**
A way to group commits by both type _and_ scope, like so:

```json
{
"changelog-sections": [
{ "type": "feat", "section": "✨ Features" },
{ "type": "fix", "section": "🐛 Bug Fixes" },
{ "type": "perf", "section": "⚡ Performance Improvements" },
{ "type": "chore", "section": "🔧 Other Changes" },
{ "type": "chore", "scope": "deps", "section": "📦 Dependencies" }
]
}
```

The above configuration would create a separate section in the changelog for any commits detected to be of the signature `chore(deps)`.