Add GrpcWeb middleware

Co-authored-by: Kevin Pollet <pollet.kevin@gmail.com>

integration/fixtures/k8s/01-traefik-crd.yml

@@ -967,6 +967,17 @@ spec:
                       forward) all X-Forwarded-* headers.'
                     type: boolean
                 type: object
+              grpcWeb:
+                description: GrpcWeb holds the gRPC web middleware configuration.
+                  This middleware converts a gRPC web request to an HTTP/2 gRPC request.
+                properties:
+                  allowOrigins:
+                    description: AllowOrigins is a list of allowable origins. Can
+                      also be a wildcard origin "*".
+                    items:
+                      type: string
+                    type: array
+                type: object
               headers:
                 description: 'Headers holds the headers middleware configuration.
                   This middleware manages the requests and responses headers. More