More Default CORS Rules (#7915)

* even more cors

* terence feedback

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

beacon-chain/flags/base.go

@@ -70,7 +70,7 @@ var (
 		Name: "grpc-gateway-corsdomain",
 		Usage: "Comma separated list of domains from which to accept cross origin requests " +
 			"(browser enforced). This flag has no effect if not used with --grpc-gateway-port.",
-		Value: "http://localhost:4242,http://127.0.0.1:4242,http://localhost:4200,http://0.0.0.0:4242,http://0.0.0.0:4200",
+		Value: "http://localhost:4200,http://localhost:7500,http://127.0.0.1:4200,http://127.0.0.1:7500,http://0.0.0.0:4200,http://0.0.0.0:7500",
 	}
 	// MinSyncPeers specifies the required number of successful peer handshakes in order
 	// to start syncing with external peers.