add list partitions for flinkcatalog

[zhangjun0x01]

show partitions of table is very common required,I think we should add the funtions.

[openinx]

Sounds good to me, we might need to implement those methods in FlinkCatalog:

  @Override
  public List<CatalogPartitionSpec> listPartitions(ObjectPath tablePath)
      throws CatalogException {
    throw new UnsupportedOperationException();
  }

  @Override
  public List<CatalogPartitionSpec> listPartitions(ObjectPath tablePath, CatalogPartitionSpec partitionSpec)
      throws CatalogException {
    throw new UnsupportedOperationException();
  }

  @Override
  public List<CatalogPartitionSpec> listPartitionsByFilter(ObjectPath tablePath, List<Expression> filters)
      throws CatalogException {
    throw new UnsupportedOperationException();
  }

[zhangjun0x01]

In the first PR, I currently only implement the first method listPartitions(ObjectPath tablePath).

the listPartitions(ObjectPath tablePath, CatalogPartitionSpec partitionSpec) method requires a CatalogPartitionSpec parameter, and the type of the CatalogPartitionSpec#partitionSpec is Map<String, String>. I tested it, the filter in iceberg needs to match the value and type.
For example, if the partition type is int, we need to pass 123. pass "123" is wrong, so I think we may need to improve the CatalogPartitionSpec#partitionSpec of flink to Map<String, Object> so that more compatibility

The listPartitionsByFilter(ObjectPath tablePath, List<Expression> filters) method need to transform the expression of flink to the expression of iceberg. I think it will also need a lot of work.

So I think we can implement the first method first, and then implement the other two methods in sub-PR later.