Avro: Fix pruning columns when a logical-map array's value type is nested

[lxynov]

Added a unit test which fails without the change

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Consider type map(long, list<long>) (a logical-map array in Iceberg-Avro) and a full projection.

In GetProjectedIds::map, the key id and value id won't be added if the value type is nested.

  public Set<Integer> map(Types.MapType map, Set<Integer> keyResult, Set<Integer> valueResult) {
    if (valueResult == null) {
      for (Types.NestedField field : map.fields()) {
        fieldIds.add(field.fieldId());
      }
    }
    return fieldIds;
  }

Missing the key id can pose a problem in PruneColumns::array, since the array's child record's key field will be omitted.

[rdsr]

+1