fix: preserve query string from X-Forwarded-Uri in decision handler

[LennartKoot]

This PR sets the r.URL.RawQuery to a potential query string provided within the X-Forwarded-Uri header. This was dropped in an earlier version because including it in the path broke the URL matcher, but fully stripping the query string breaks authenticator that rely on query parameters.

Related issue(s)

#1264

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