[Python] Add sort_by method to Array, StructArray and ChunkedArray

[asfimport]

It would be convenient to be able to sort a StructArray on one of its columns. This can be done by combining multiple compute functions, but having a helper that does that for you would probably be better.

Reporter: Alessandro Molina / @amol-
Assignee: Alessandro Molina / @amol-

PRs and other links:

• GitHub Pull Request #14369

_{Note: This issue was originally created as ARROW-14656. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
This would probably be more useful as a C++ addition.

[asfimport]

Antoine Pitrou / @pitrou:
Ah, now I see the PR, I understand. I thought you wanted to sort the entire structarray (all the columns).

[asfimport]

Krisztian Szucs / @kszucs:
Postponed to 9.0

[jorisvandenbossche]

This was essentially implemented by #14781 (and so a duplicate of #14778), as far as I understand. Thus closing this issue.

[jorisvandenbossche]

Duplicate of #14778