[C++][Python] UDF Scalar Function Implementation

[asfimport]

Here we will include the concrete UDF implementation for Scalar functions

Reporter: Vibhatha Lakmal Abeykoon / @vibhatha
Assignee: Vibhatha Lakmal Abeykoon / @vibhatha

PRs and other links:

• GitHub Pull Request #12590

_{Note: This issue was originally created as ARROW-15639. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 12590
#12590