Change UDF signature to use ColumnarValue rather than raw Arrow types

[andygrove]

What is the problem the feature request solves?

Is your feature request related to a problem or challenge?

DataFusion uses ColumnarValue to represent Arrays and Scalars.

#[derive(Clone, Debug)]
pub enum ColumnarValue {
    /// Array of values
    Array(ArrayRef),
    /// A single value
    Scalar(ScalarValue),
}

Perhaps we should use this in the UDF signatures. This avoids the need to pass in row counts.

Describe the solution you'd like

No response

Describe alternatives you've considered

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Additional context

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Describe the potential solution

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Additional context

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[mbutrovich]

Are you referring specifically to CometUDF? Does that make DataFusion Java a dependency?