Secret scanning: Support push protection for custom patterns

[github-product-roadmap]

Summary

In public beta, secret scanning scans high-confidence tokens (those with a low false positive rate) and blocks a remote push if secrets are detected, thereby flagging secrets before exposure. Now, we're expanding push protections to support custom patterns!

Intended Outcome

Advanced Security customers can enable push protection for our set of highly-identifiable, built-in patterns. While these patterns provide preventative support for customers, organizations want to also protect their developers from leaking organization-specific patterns. Push protection support for custom patterns will fill this coverage need.

How will it work?

Advanced Security customers will be able to enable push protection for default patterns and custom patterns at the repository and organization levels.