Request to add custom providers like Azure, GCP, etc

Also mentioned in #150 #171

I see forks (e.g. https://github.com/deshpandetanmay/git-secrets and https://github.com/msalemcode/git-secrets) adding GCP and Azure patterns, here I just want to confirm whether you are open to custom providers, and we can definitely provide patterns and contribute.

The issue names no files, tests, or entry points. First review the related issues #150 and #171 and the referenced fork changes to establish the intended provider-pattern scope. Done would require an agreed contribution plan for custom providers, followed by implementation and validation details that are not specified here.

Written by the indexing model from the issue text.