fix: check leaf column is root column in Parquet schema (#1347)

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N/A

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This PR is to fix a bug in checking if a leaf column is root column in
Parquet schema. The current solution is to compare the leaf column's
index with root column's index, this is not reliable as the column index
may not correspond exactly after a nested column. For example,

- col A: String
- col B: Map
  - key B.K: String
  - value B.V: String
- col C: String

For column A, B.K and B.V, the currently logic works well. It won't
return error for A, but will do for B.K and B.V, this is correct. But
for column C, it will return error as its leaf column index (3) will not
match root column index (2), this is incorrect. Column C is a valid leaf
column to be in a predicate.

I think `get_column_root().is_group()` may be a more reliable way to
check in this situation. Just to check if a leaf column's root column is
a group column, we can determine a leaf column is actually on the root.

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Yes

Author: burmecia

crates/iceberg/src/arrow/reader.rs

@@ -933,7 +933,7 @@ impl PredicateConverter<'_> {
     fn bound_reference(&mut self, reference: &BoundReference) -> Result<Option<usize>> {
         // The leaf column's index in Parquet schema.
         if let Some(column_idx) = self.column_map.get(&reference.field().id) {
-            if self.parquet_schema.get_column_root_idx(*column_idx) != *column_idx {
+            if self.parquet_schema.get_column_root(*column_idx).is_group() {
                 return Err(Error::new(
                     ErrorKind::DataInvalid,
                     format!(