[Feat] Support Merge-on-Read mode for Deletes

### Feature Request / Improvement

Similar to Spark, we would like to implement Merge-on-Read mode of deleting, by creating delete files that encode position and equality delete markers that can be applied within a given partition.

https://iceberg.apache.org/spec/?h=delete+files#row-level-deletes

Start by reading the Apache Iceberg row-level deletes specification linked in the issue, then compare its position and equality delete requirements with the existing PyIceberg deletion behavior. Define the supported Merge-on-Read scope and verify that delete markers can be applied within a partition, including tests for both delete types.

Written by the indexing model from the issue text.