feat: submit verification token through API

[splaunov]

Verification links are delivered by email and supposed to be used with a browser. But if mobile app registers the URL, the user will be promoted to open the link in the app. In this scenario mobile app should be able to extract flow id and the token from the link and submit it to kratos API. As for now, this will redirect to verification UI and mobile app will not be able to process the result of the call in a simple way.

This PR adds better support to verification token validation through API calls.

Related issue(s)

Checklist

• [ x] I have read the contributing guidelines.
• [ ] I have referenced an issue containing the design document if my change introduces a new feature.
• [ x] I am following the contributing code guidelines.
• [ 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 green light (please contact [email protected]) from the maintainers to push the changes.
• [ x] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have added or changed the documentation.

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