feat(r): Evaluate SedonaDBExpr and add basic roundtrip tests #484
Description
After #468 we can convert an R expression to a SedonaDB expression but we can't evaluate it and we don't have any idiom or helper to roundtrip test. Once we have a good system for simple evaluation and roundtrip testing LLMs can probably help with the translations. This almost certainly involves handling separating the aggregations/window functions from the scalar functions to create a logical plan (I think there is a helper in DataFusion for this).