move to bi-directional streaming for source, map, transformer, and sink for better performance

[vigith]

Summary

The integration between numa and SDK server should be via gRPC Streaming and not unary for better performance. We should even move half-duplex to bi-di.

Use Cases

Getting Numaflow ready for future performance improvements.

Tasks

Beta Give feedback

1. Streaming Source #2045
   6 of 7
   +0
   
2. Add Stop and Stopped to Source gRPC (no-op)
3. Streaming Transformer #2046
   5 of 6
   +0
   
4. Streaming Map #2092
   4 of 6
   +0
5. Streaming Sink #2091
   6 of 7
   +0
   

---

Message from the maintainers:

If you wish to see this enhancement implemented please add a 👍 reaction to this issue! We often sort issues this way to know what to prioritize.