Support encoded path in router (#1347)

Encoded path means the URL path contains encoded string like "/foo%2Fbar".
Gorilla/Mux by default doesn't enable encoded path support, you need to enable
it when initializing the router.

This PR adds a new environment variable USE_ENCODED_PATH to the router
deployment to enable encoded path support.

charts/fission-core/values.yaml

@@ -53,6 +53,12 @@ router:
   ## Add annotations for router
   # svcAnnotations:
   #   cloud.google.com/load-balancer-type: Internal
+  
+  ## For router to match encoded path.
+  ## If true, "/foo%2Fbar" will match the path "/{var}";
+  ## Otherwise, it will match the path "/foo/bar".
+  useEncodedPath: false
+  
   roundTrip:
     ## If true, router will disable the HTTP keep-alive which result in performance degradation.
     ## But it ensures that router can redirect new coming requests to new function pods.