Touch up some of the interfaces and docs in vortex-datafusion

[AdamGS]

Summary

This PR mostly touches up some of the interfaces, and exposes a few extra types that might be helpful for users.

1. Makes our type conversion traits public
2. Exposes DefaultExpressionConverter, so users can fall back to it if they need to in their own implementations.
3. VortexSink if they want to explore write physical plans
4. Introduces VortexSource::predicate, to explore read physical plans.

[codspeed-hq]

Merging this PR will improve performance by 33.68%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚡ 4 improved benchmarks
✅ 1577 untouched benchmarks
⏩ 3 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	chunked_bool_canonical_into[(1000, 10)]	34.9 µs	20.5 µs	+69.78%
⚡	Simulation	bitwise_not_vortex_buffer_mut[128]	244.4 ns	186.1 ns	+31.34%
⚡	Simulation	bitwise_not_vortex_buffer_mut[1024]	304.7 ns	246.4 ns	+23.68%
⚡	Simulation	bitwise_not_vortex_buffer_mut[2048]	427.8 ns	369.4 ns	+15.79%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing adamg/add-some-df-apis (734821a) with develop (4f52cbc)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩