[Rust] [DataFusion] Add support for generic return types of scalar UDFs

[asfimport]

Currently, we have math functions declared as UDFs that while they can be evaluated against float32 and float64, their return type is fixed (float64).

This issue is about extending the UDF interface to support generic return types (a function), so that developers (us included), can register UDFs or variable return types.

There is a small overhead in this, since evaluating types now requires a function call, however, IMO this is still very small when compared to anything, as we are talking about plans. We can always apply some caching if needed.

Reporter: Jorge Leitão / @jorgecarleitao
Assignee: Jorge Leitão / @jorgecarleitao

PRs and other links:

• GitHub Pull Request #7974

_{Note: This issue was originally created as ARROW-9756. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
@jorgecarleitao this is pretty stale and presumably you've duplicated this issue to arrow-rs and/or already resolved it, right?

[asfimport]

Jorge Leitão / @jorgecarleitao:
yes, it already merged and got lost in the migration. Thanks for closing it. 👍