feat: for expired challenges return HTTP 410 and redirect url

[terev]

Return HTTP 410 and initial auth url for consent app to redirect user agent to when an expired challenge is supplied. This implements the same mechanism provided for consent apps to handle previously utilized challenges #2473 .

BREAKING CHANGES: This patch changes the response status code for expired challenges from 401 to 410. It also changes the schema of the response from fosite.RFC6749Error to flow.OAuth2RedirectTo.

Related issue(s)

Closes #3772

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