Code host integration for npmjs.com

Created by: LinqLover

Feature request description

I often visit an npm package and would like to search its implementation using Sourcegraph. A quick button to view the repository on sourcegraph.com would be helpful for this.

Is your feature request related to a problem? If so, please describe.

No, this would just be a convenience feature.

Describe alternatives you've considered.

At the moment, I always need to go the GitHub/GitLab/... repository manually (which is linked on npmjs.com) and then head to Sourcegraph from there.

Additional context

The same would be possible for other package repositories such as pypi.org etc., too.