Execution::Next dataloader / lazy

[rmosolgo]

Working on the next round of #5509

• Basic dataloader hookup
• Basic lazy support
• context[:current_path] I honestly think this might be basically impossible to do in a high-performance way. Currently it's only applied after-the-fact to errors. I think I'm going to address other TODOs first.
• raw_value
• Fix skip(...)s and TODOs I'll address these in the target