Use schema visitor in ArrowReader name mapping

### Is your feature request related to a problem or challenge?

#1821 will add `apply_name_mapping_to_arrow_schema` to `ArrowReader` but might not handle nested types properly.

### Describe the solution you'd like

We should use a visitor to handle nested fields.

### Willingness to contribute

I can work on this.

Start by reviewing ArrowReader and the proposed apply_name_mapping_to_arrow_schema change from #1821. Trace how schema fields are currently mapped, especially nested fields, and identify the visitor entry point. Done means name mapping is handled consistently for nested types as well as top-level fields.

Written by the indexing model from the issue text.