feat: implement checkpointing and state persistence for Parquet Reader and FileSource

[Meghajit]

As part of this issue, we want to add state persistence to the Parquet File Source. Basically, if the Dagger job gets stopped due to some reasons, the job should resume from a reliable state and should not start processing all the parquet files again from the beginning.

[Meghajit]

This was done and merged as part of PR: #163