feat: add support for none response_type

[dtam-cybozu]

This PR adds support for the none response_type specified in https://openid.net/specs/oauth-v2-multiple-response-types-1_0.html#none

Related Issue or Design Document

This was brought up before here #409

Checklist

• I have read the contributing guidelines and signed the CLA.
• I have referenced an issue containing the design document if my change introduces a new feature.
• 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 approval (please contact [email protected]) 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

I still need to add non-unit tests but I'd prefer to do this after I've received confirmation that this feature and this approach is okay. This is also quite a small feature so perhaps extensive testing of it is not completely necessary - please let me know how much testing you're expecting for this!

I also need to add something to the changelog.

[sword-jin]

a few suggesstions

[sword-jin]

I think this encapsulation is not readable, since secureChecker has no more caller.

You can just change secureChecker to secureCheck, pass the uri to it

[dtam-cybozu]

Thanks, actually most of this file is copy pasted from https://github.com/ory/fosite/blob/master/handler/oauth2/flow_authorize_code_auth.go so I've just copied the style from that file.