Add Unsubscribe API for Configuration building block

[mukundansundar]

dapr/dapr#4130 changes proto files to add unsubscribe API as well as additional fields to existing configuration API response.

Implement the unsubscribe API as well as add in the additional fields necessary for the change to include ID field in subscribe API to track for stopping subscription.

Release Note

RELEASE NOTE: Add unsubscribe API.

[mukundansundar]

@artursouza

[pravinpushkar]

/assign

[pravinpushkar]

@mukundansundar Verified this with dapr master and proto file, it works fine. There is no change needed at Java-sdk level.

We can close this issue.

[mukundansundar]

@pravinpushkar Interesting ... We are not using the full SubscribeConfigurationResponse anywhere ... Which is kind of expected since it only contained List till the above PR.
Now it has an ID field too ... which is used for unsubscribe API.

I will keep this issue open and change the title to implement unsubscribe API. Then we would need the proto changes that were made in dapr/dapr. https://github.com/dapr/dapr/pull/4130/files#diff-da511bac0105b1e517ff78c6351b68bda0d5862cb0daae89127f6c0250551265R528

[mukundansundar]

I have added a breaking changes label since I believe the exposed API in the preview client will change to include the SubscribeConfigurationResponse.