[Task]: Data Sampling

[rohdesamuel]

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
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