Add SubscribeTopicEvents for PUB/SUB

[wenxuwan]

What would you like to be added:

Layotto currently uses a callback method for message subscription, which is not friendly to developers. The SubscribeTopicEvents interface can be added to allow developers to actively trigger message subscriptions.

Why is this needed:

Allows developers to use Pub/Sub capabilities more conveniently without applying the test to start the GRPC service.

can refer https://github.com/dapr/dapr/blob/master/dapr/proto/runtime/v1/dapr.proto#L64

[github-actions]

Hi @wenxuwan,
Thanks for opening an issue! 🎉

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity in the last 30 days. It will be closed in the next 7 days unless it is tagged (pinned, good first issue or help wanted) or other activity occurs. Thank you for your contributions.

[github-actions]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as pinned, good first issue or help wanted. Thank you for your contributions.