arrow

GH-34278: [C++] Expose schema in named table provider (#34279)



### Rationale for this change

https://github.com/apache/arrow/issues/34278
### What changes are included in this PR?
This PR adds an parameter "schema" in the `NamedTableProvider` interface

### Are these changes tested?
Added test to check schema in named table provider

### Are there any user-facing changes?
This is a developer API change.

Authored-by: Li Jin <ice.xelloss@gmail.com>
Signed-off-by: Weston Pace <weston.pace@gmail.com>