[Feature] Support broadcast messages in http sub mode

I have download the code and run the eventmesh with tcp/http mode, but i want to use broadcast mode in http, when i run more than one application in consumer group , only one application can receieve the message from the topic which they subscribe.

No files or tests are named. Start by tracing HTTP subscription handling and how messages are routed among applications in a consumer group. Define the broadcast behavior for HTTP mode, then verify that every subscribed application receives each topic message rather than only one.

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