feat: add ResponseModeHandler to support custom response modes

[narg95]

Related issue

#591

Proposed changes

This is a draft/preview PR of the proposed change described in issue #591

Status

• Main functionality is implemented
• Existing Unit tests pass
• Missing:
  • Add ResponseModeHandler in compose.Config package
  • Add extra unit test
  • Document public interface and source code

Checklist

• I have read the contributing guidelines
  and signed the CLA.
• I have read the security policy.
• 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 green light (please contact
  security@ory.sh) from the maintainers to push
  the changes.
• [x ] I have added tests that prove my fix is effective or that my feature
  works.
• [x ] I have added necessary documentation within the code base (if
  appropriate).

[aeneasr]

I think this is going in the right direction! Would definitely need a few more tests, especially integration tests :)

[narg95]

sure, bu I was thinking in unit tests, why did you consider integration tests if this change is not integrating with a DB or external processes, or what kind of integration tests you mean? Can you point me in the right direction?

[aeneasr]

Ah sure, I was thinking of a test in the direction of https://github.com/ory/fosite/blob/master/integration/authorize_form_post_test.go which would use a custom response mode. Does that make sense?

[narg95]

Sure, makes sense, I will use it as a base

[narg95]

@aeneasr done!
I added integration tests, at first I copied form_post tests but soon I realized I could better reuse them with some flags so that there is no need to maintain two sets of similar test cases.

Let me know if that would be enough to merge this PR

[aeneasr]

Once ory/hydra#2526 is merged we can re-run the conformity tests here which should then pass :)

[narg95]

@aeneasr today's merged commits in hydra and fosite seem to work :)
I rebased this branch with latest commits and got OpenID Connect Conformity Tests 🟢 green :)

[aeneasr]

Awesome, thank you for your contribution!