Make Subscriptions available in dotnet client sdks DaprMetadata

[umerkle]

Describe the feature

DaprMetadata does deliver information about current subscriptions as of this documentation: Metadata API

Currently only Id, Actors, Components and Extended are available in DaprMetadata class. So there should be also a Subscriptions property.

Release Note

RELEASE NOTE: ADD Information about pubsub subscriptions.

[philliphoff]

@umerkle While I generally agree with exposing most metadata that the application can provide, do you have a practical example of how that data might be used (that could, for example, help inform how best that information can be exposed).

[umerkle]

@philliphoff I am mostly interested in the list of subscriptions. I want to see to which topics the app has subscribed. I want to 'inspect' that app from another app to show informations about its capabilities. Later on, informations about workflows could also be interesting for the same reason.

[halspang]

@umerkle - Generally the metadata API is only called on the local sidecar. Have you been able to call it from a remote app via the DaprClient?

[umerkle]

@halspang The idea is to call the app and the app uses it's DaprClient to call the local sidecar.