Create a GitHub Action to automatically label "source" on issues

[travishathaway]

Checklist

• I added a descriptive title
• I searched open requests and couldn't find a duplicate

What is the idea?

When a new issue is created by a specific conda team member in charge of managing the repository, issues in the repository should be tagged with source::contributor.

Why is this needed?

This will give us a nice way to automatically organize issues coming from maintainers vs. issues coming from everyone else.

What should happen?

Create a GitHub Action that will:

• Run each time a new issue is created
• Figure out which groups are responsible for maintaining the repository
• Add the source::contributor label to an issue if the reporter is in any of the above groups

Additional Context

No response

[jezdez]

I think this has overlap with conda/governance#86 and conda/governance#147 which would make this more automatable, I agree this would be neat.