JS: Add proxy as a route handler name

Author: asgerf

javascript/ql/lib/semmle/javascript/frameworks/Next.qll

@@ -310,7 +310,8 @@ module NextJS {
         )
       |
         this =
-          mod.getAnExportedValue([any(Http::RequestMethodName m), "middleware"]).getAFunctionValue()
+          mod.getAnExportedValue([any(Http::RequestMethodName m), "middleware", "proxy"])
+              .getAFunctionValue()
       )
     }