[C++][Python] Generate scalar-argument kernel based on array-argument kernel for UDFs

[asfimport]

When defining UDFs the ability to use a function on both scalar and array with a single function definition is important. Here using a function just written for array-like inputs on scalars is a vital component when providing better support. Further more, UDFs need to be consistent with the pre-registered functions in the function registry. Considering both usability and consistency, it is important to support this feature. 

This requirement was a part of discussion in Scalar UDF integration PR[1]. 

 

References:

 

[1]. #12590 (comment)

Reporter: Vibhatha Lakmal Abeykoon / @vibhatha

_{Note: This issue was originally created as ARROW-16213. Please see the migration documentation for further details.}

[asfimport]

Todd Farmer / @toddfarmer:
This issue was last updated over 90 days ago, which may be an indication it is no longer being actively worked. To better reflect the current state, the issue is being unassigned per project policy. Please feel free to re-take assignment of the issue if it is being actively worked, or if you plan to start that work soon.