fix: preserve async UDF return field metadata

[Kontinuation]

Which issue does this PR close?

Closes #22662.

Rationale for this change

Async scalar UDFs can compute output field metadata in return_field_from_args(...), but AsyncFuncExpr rebuilt the output field from only name, data type, and nullability. This dropped metadata from async UDF result fields.

What changes are included in this PR?

This PR updates AsyncFuncExpr::field(...) to preserve the planned return_field metadata and only rename the field for the async expression output.

It also adds a regression test that verifies an async UDF result batch preserves metadata attached by return_field_from_args(...).

Are these changes tested?

Yes.

Added a regression test in:

• datafusion/core/tests/user_defined/user_defined_async_scalar_functions.rs

The test fails without the fix and passes with the fix.

Are there any user-facing changes?

Yes.

Async scalar UDF result fields now preserve metadata attached by return_field_from_args(...).

[paleolimbot]

To the extent that I'm qualified to approve these things, this looks good to me!

[Jefffrey]

i wonder if we're better off deprecating this function and do something similar to ScalarFunctionExpr and implement PhysicalExpr::return_field 🤔

datafusion/datafusion/physical-expr/src/scalar_function.rs

Lines 283 to 285 in e2db766

	fn return_field(&self, _input_schema: &Schema) -> Result<FieldRef> {
	Ok(Arc::clone(&self.return_field))
	}

[Kontinuation]

Good idea. I have updated the PR to deprecate fn field and implemented fn return_field.

[github-actions]

Thank you for opening this pull request!

Reviewer note: cargo-semver-checks reported the current version number is not SemVer-compatible with the changes in this pull request (compared against the base branch).

Details

     Cloning apache/main
    Building datafusion v53.1.0 (current)
       Built [  98.898s] (current)
     Parsing datafusion v53.1.0 (current)
      Parsed [   0.036s] (current)
    Building datafusion v53.1.0 (baseline)
       Built [ 100.064s] (baseline)
     Parsing datafusion v53.1.0 (baseline)
      Parsed [   0.035s] (baseline)
    Checking datafusion v53.1.0 -> v53.1.0 (no change; assume patch)
     Checked [   0.627s] 223 checks: 223 pass, 30 skip
     Summary no semver update required
    Finished [ 202.847s] datafusion
    Building datafusion-physical-expr v53.1.0 (current)
       Built [  28.506s] (current)
     Parsing datafusion-physical-expr v53.1.0 (current)
      Parsed [   0.048s] (current)
    Building datafusion-physical-expr v53.1.0 (baseline)
       Built [  28.969s] (baseline)
     Parsing datafusion-physical-expr v53.1.0 (baseline)
      Parsed [   0.051s] (baseline)
    Checking datafusion-physical-expr v53.1.0 -> v53.1.0 (no change; assume patch)
     Checked [   0.355s] 223 checks: 222 pass, 1 fail, 0 warn, 30 skip

--- failure type_method_marked_deprecated: type method #[deprecated] added ---

Description:
A type method is now #[deprecated]. Downstream crates will get a compiler warning when using this method.
        ref: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.48.0/src/lints/type_method_marked_deprecated.ron

Failed in:
  method datafusion_physical_expr::async_scalar_function::AsyncFuncExpr::field in /home/runner/work/datafusion/datafusion/datafusion/physical-expr/src/async_scalar_function.rs:92

     Summary semver requires new minor version: 0 major and 1 minor checks failed
    Finished [  59.206s] datafusion-physical-expr
    Building datafusion-physical-plan v53.1.0 (current)
       Built [  36.056s] (current)
     Parsing datafusion-physical-plan v53.1.0 (current)
      Parsed [   0.127s] (current)
    Building datafusion-physical-plan v53.1.0 (baseline)
       Built [  36.035s] (baseline)
     Parsing datafusion-physical-plan v53.1.0 (baseline)
      Parsed [   0.126s] (baseline)
    Checking datafusion-physical-plan v53.1.0 -> v53.1.0 (no change; assume patch)
     Checked [   0.613s] 223 checks: 223 pass, 30 skip
     Summary no semver update required
    Finished [  75.169s] datafusion-physical-plan