[Enhancement] Expose More Metadata in Object APIs

[chenghuichen]

Currently, pypaimon's object APIs are designed to be minimal, lacking exposure of certain metadata fields that could be beneficial for external framework to optimize read/write strategies. For instance, the Ray datasource framework requires additional information such as file sizes for each read split. We propose to enhance the object APIs by exposing more comprehensive metadata.

[RSzipper]

could you describe the issue in detail please i found it unclear to understand please help me out