GH-44446: [C++][Python] Add mask creation helper

[amol-]

Rationale for this change

Implement a convenience method to create boolean masks where only some rows are set to true

What changes are included in this PR?

C++ MakeMaskArray factory function and pyarrow.mask Python factory function

Are these changes tested?

Yes both C++ and Python

Are there any user-facing changes?

Yes, new API has been added

• GitHub Issue: #44446

[github-actions[bot]]

:warning: GitHub issue #44446 has been automatically assigned in GitHub to PR creator.

[amol-]

@pitrou Do you have time to review? I think this is more or less done

[amol-]

I think the two failures are unrelated to this branch. For Java it seems to be a memory leak in FlightSQL

Error:    TestFlightSqlStreams.tearDown:238 » IllegalState Memory was leaked by query. Memory leaked: (81920)

And for R it seems related to datetimes

── Failure ('test-dplyr-funcs-datetime.R:302:5'): timestamp round trip correctly via strftime and strptime ──

[amol-]

When you have the chance I'd appreciate if you could re-review this one @pitrou 🙂