Add grpc keepalive pings to all SDKs

GRPC keepalive pings is a performance best practice for GRPC clients https://grpc.io/docs/guides/performance/.

In the case of dapr it can also benefit the interactions with the workflows API and the GRPC stream that it creates, since this GRPC stream can be idle for long periods of time, and without a keepalive the connection can be unnecessarily closed. Specifically in the case of the workflows API closing this stream can pause the processing of workflows, so its vital to keep it open as long as possible even if idle.

Start with the proposal body and the linked gRPC performance guide, then identify the SDK repositories and client entry points that create the workflows API and gRPC streams. The issue names no files or tests; done means keepalive pings are configured across all SDKs so idle streams remain open without unnecessary connection closure.

Written by the indexing model from the issue text.