Add tracing to the new runtime

### Is your feature request related to a problem or challenge?

DataFusion has a nice [JoinSetTracer](https://docs.rs/datafusion-common-runtime/latest/datafusion_common_runtime/trait.JoinSetTracer.html) where a user can inject their own tracing or metrics. I think it would be valuable for us to have our own version in iceberg-rust.

### Describe the solution you'd like

_No response_

### Willingness to contribute

I can contribute to this feature independently

Start by reading DataFusion's JoinSetTracer documentation linked in the issue and locating the new runtime entry points in iceberg-rust. Define the tracing or metrics injection surface and verify that the runtime exposes an equivalent capability with coverage for its intended use cases.

Written by the indexing model from the issue text.