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

[sungwy]

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

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[Fokko]

Or we can jump directly to deletion vectors 😏

[piyushdubey]

Reviving this thread. Is the support for Writing Position Deletes added to PyIceberg or not yet?

@Fokko, @sungwy