Use uniform Socket message size to avoid disconnects

Summary: During startup the socket connection would close a few times, among others because Scribe dumps 1.3 MB of data after startup, and the maximum payload of `socket.io` defaults to 1MB. This diff changes it to 100MB (the max size used by `ws` library). We know that we need at least > 10 MB, as that is what plugins like Network cap at.

Reviewed By: aigoncharov

Differential Revision: D33017653

fbshipit-source-id: 1233af6fbdc4b9eed42786ee418cfd6d43b2b433

desktop/flipper-server-core/src/index.tsx

@@ -26,3 +26,5 @@ export function getGatekeepers(username: string): Record<string, boolean> {
   }
   return GKImplementation.allGKs();
 }
+
+export {WEBSOCKET_MAX_MESSAGE_SIZE} from './comms/ServerWebSocket';