spoolman: Add spoolman response headers to proxy results

Added the response headers to the V2 response of the proxy implementation as a new field named "response_headers".

Signed-off-by: Patrick Schmidt <ps.patti1998@gmail.com>

moonraker/components/spoolman.py

@@ -373,6 +373,7 @@ class SpoolManager:
         else:
             return {
                 "response": response.json(),
+                "response_headers": dict(response.headers.items()),
                 "error": None
             }