Missing message id check in defineCustomEventMessaging

[stotiks]

Currently, there's no message id verification (detail.message.id === requestEvent.detail.message.id) in the responseListener. This omission can lead to mismatched responses when multiple messages are in flight simultaneously, as responses might be incorrectly paired with unrelated requests.

https://github.com/aklinker1/webext-core/blob/684feda2bf8304cf7bafa9e94a436880e855f691/packages/messaging/src/custom-event.ts#L75

Thanks!