GH-45669: [C++][Parquet] Add missing ParquetFileReader::GetReadRanges() definition (#45684)

### Rationale for this change

We only have a definition of it in an implementation private class but it's not defined in public `ParquetFileReader` class.

### What changes are included in this PR?

Define `ParquetFileReader::GetReadRanges()` .

### Are these changes tested?

Yes.

### Are there any user-facing changes?

Yes.
* GitHub Issue: #45669

Authored-by: Sutou Kouhei <[email protected]>
Signed-off-by: Sutou Kouhei <[email protected]>

Author: kou

cpp/src/parquet/file_reader.cc

@@ -923,6 +923,16 @@ void ParquetFileReader::PreBuffer(const std::vector<int>& row_groups,
   file->PreBuffer(row_groups, column_indices, ctx, options);
 }
 
+::arrow::Result<std::vector<::arrow::io::ReadRange>> ParquetFileReader::GetReadRanges(
+    const std::vector<int>& row_groups, const std::vector<int>& column_indices,
+    int64_t hole_size_limit, int64_t range_size_limit) {
+  // Access private methods here
+  SerializedFile* file =
+      ::arrow::internal::checked_cast<SerializedFile*>(contents_.get());
+  return file->GetReadRanges(row_groups, column_indices, hole_size_limit,
+                             range_size_limit);
+}
+
 ::arrow::Future<> ParquetFileReader::WhenBuffered(
     const std::vector<int>& row_groups, const std::vector<int>& column_indices) const {
   // Access private methods here