Org-level centralized private registry configuration for Dependabot [GA]

[glider-bot]

Value Prop

To enable Dependabot to use packages in private registries, GitHub Advanced Security users have to set up credentials in a dependabot.yml for every repository, which takes a long time for lots of repositories.

Expected Outcome

This feature allows GitHub Advanced Security users to configure Dependabot to access their private registries from the org level.