Sankey Visualizer - Event Flow

[Aergonus]

vector graph is great for tracing the topology and internal metrics show how much volume is being processed/dropped
but what I really want is an easy way to inflows and outflows for each component.

I'm imagining vector sankey <events,event_bytes> to link and instantaneous event counts/bytes flows.

Simple link format would be ingestible by https://observablehq.com/@mbostock/flow-o-matic and would be 90% of the way to fit https://visactor.io/vchart/guide/tutorial_docs/Chart_Types/Sankey

[Aergonus]

closing for #21853