Correct message annotation on early js errors

Summary:
## Context
When is the runtime ready?
- After the main bundle finishes executing **without** raising a fatal javascript error

## Changes
Let's decorate all errors reported while the runtime is not ready as "[runtime not ready]".


Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D66316907

packages/react-native/ReactCommon/jserrorhandler/JsErrorHandler.cpp

@@ -331,7 +331,8 @@ void JsErrorHandler::handleErrorWithCppPipeline(
   auto id = nextExceptionId();
 
   ParsedError parsedError = {
-      .message = _isRuntimeReady ? message : ("EarlyJsError: " + message),
+      .message =
+          _isRuntimeReady ? message : ("[runtime not ready]: " + message),
       .originalMessage = originalMessage,
       .name = name,
       .componentStack = componentStack,