Optimize data file conversions in Iceberg and Hudi target clients

[ashvina]

To avoid creating unnecessary object creation and converting data files multiple times, Iceberg and Hudi clients should follow the same approach as the Delta Client.

Do we want to do something similar for Iceberg and Hudi targets? Is there any way we can make this logic common?

Originally posted by @the-other-tim-brown in #326 (comment)