- Generate RM-Rate map from Items table (will include subassembly items with rate)
- Function to reset exploded item rate from above map
- `db_update` exploded item rate only if rate is changed
- Via Update Cost, only update exploded items rate, do not regenerate table again
- Exploded Items are regenerated on Save and Replace BOM job
- `calculate_exploded_cost` is run only via non doc events (Update Cost button, Update BOMs Cost Job)