Include Requested Scopes in Webhook Requests

[3schwartz]

Add requested scopes to the webhook request, allowing the webhook to condition access based on the scopes requested by the user.

Related issue(s)

Fixes #3620, particularly implementing the idea proposed in this comment: #3620 (comment).

If this PR is accepted, I can provide an update to the documentation.

Checklist

• I have read the contributing guidelines.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I am following the
  contributing code guidelines.
• 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 the 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 or changed the documentation.

Further Comments