feat: hydra & kratos integration example (#2976)

[mattbarnicle]

An example implementation of Hydra as SSO and Kratos as the Identity Provider, all running in Docker.

Related Issue or Design Document

This is related to discussion #2976, "How to configure Kratos to work with Hydra?"

Checklist

• [x] I have read the contributing guidelines and signed the CLA.
• [x] I have referenced an issue containing the design document if my change introduces a new feature.
• [x] I have read the security policy.
• [x] I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security vulnerability, I confirm that I got approval (please contact security@ory.sh) from the maintainers to push the changes.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have added the necessary documentation within the code base (if appropriate).

Further comments

[vinckr]

Thanks @mattbarnicle I think this is a good starting point! I did get some errors in the flow, but mostly worked OK. I will add some README to my branch and see to do some more testing/fixing.