perf(arrow-ipc): avoid counting nulls in RecordBatchDecoder

[rluvaton]

Which issue does this PR close?

N/A

Rationale for this change

The Arrow IPC format already contain the null count for each array, reusing it instead of calculating each time to improve performance

What changes are included in this PR?

Update the create_array in RecordBatchDecoder to use the null count when creating ArrayDataBuilder

Are these changes tested?

Existing tests

Are there any user-facing changes?

No

[alamb]

Thanks @rluvaton -- the code looks good to me

I wonder if you think we should add any new tests to cover this new path, or if you have any benchmarks we should run that might show an improvement?

[rluvaton]

Not sure about adding a test, I can add a test for creating an invalid null length and see that it fails, but this will have the same result before and now, so that test should already exist regardless.

and about benchmarks, no I did not run any nor do I have any, any IPC reading benchmark for arrays that have nulls in them will suffice.

[Dandandan]

LGTM, null counting probably is probably not the most expensive part, but good to avoid it regardless :)

[alamb]

Thanks @rluvaton and @Dandandan