What needs to happen?

This issue is to track adding a data sampling feature to the SDKs as discussed in the associated slide deck. This adds:

• The Sample instruction (SampleRequest and SampleResponse) to query the samples from an SDK
• The "beam:protocol:data_sampling:v1" capability to track which SDKs can sample
• The "enable_data_sampling" experiment to toggle the feature
• Automatic sampling in the Python, Java, and Go SDKs for running PTransforms

Issue Priority

Priority: 3 (nice-to-have improvement)

Issue Components

• Component: Python SDK
• Component: Java SDK
• Component: Go SDK
• Component: Typescript SDK
• Component: IO connector
• Component: Beam examples
• Component: Beam playground
• Component: Beam katas
• Component: Website
• Component: Spark Runner
• Component: Flink Runner
• Component: Samza Runner
• Component: Twister2 Runner
• Component: Hazelcast Jet Runner
• Component: Google Cloud Dataflow Runner