Scalar is not exported as part of arrow (it is only exported in arrow_array)

[alamb]

Describe the bug

the newly introduced Scalar is not exported as part of arrow (it is only exported in arrow_array)

https://docs.rs/arrow-array/46.0.0/arrow_array/struct.Scalar.html

While I appreciate the desire to have more granular crates in arrow, forcing end users to explicitly use subcrates (and thus also patch them / keep them up to date) is inconvenient

To Reproduce

Look for scalar in Arrow
https://docs.rs/arrow/latest/arrow/index.html?search=scalar

Expected behavior
Perhaps a good way to fix this would be to explicitly re-export all of arrow_array rather than just a subset https://github.com/apache/arrow-rs/blob/master/arrow/src/array/mod.rs 🤔

Additional context
I found this while working through https://github.com/influxdata/influxdb_iox/pull/8577 (the upgrade to arrow 46 in IOx) and updating to use the new kernels

[tustvold]

I definitely think it would be good to revisit the layout of the top-level arrow crate to better reflect the crate topology. Ideally as you say it would just re-export the underlying crates as is

[tustvold]

label_issue.py automatically added labels {'arrow'} from #4791