Unify id creation for ScalarFns and rename is_null to vortex.is_null

[robert3005]

Use ScalarFnId::from instead of new_ref and rename is_null fn to vortex.is_null

Signed-off-by: Robert Kruszewski github@robertk.io

[codspeed-hq]

Merging this PR will degrade performance by 14.84%

❌ 1 regressed benchmark
✅ 1121 untouched benchmarks
⏩ 1530 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	chunked_bool_canonical_into[(1000, 10)]	50.1 µs	58.8 µs	-14.84%

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_{Comparing rk/names (1c8bf29) with develop (06065ff)}

Footnotes

1. 1530 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. ↩

[joseph-isaacs]

should be namespace these into vortex.scalar_fn... or something else?

Also while we are here what dynamic expr is this?

[robert3005]

haha, DynamicComparisonExpr