[Issue] Combined Products Should Be Supported On Gastro 5x

[Blair2004]

Describe the bug
There is an option on NexoPOS that merges similar products on the receipt. This helps reducing the length of the paper and then reduce waste. Unfortunately, the feature doesn't works on Gastro as this type of combined product (which is not a grouped product) doesn't have any id, therefore Gastro is not able to properly pull modifiers that might be attached to those products.

To Reproduce
Steps to reproduce the behavior:

1. Enable "Merge Similar Products" on the invoice settings
2. Make a sale for similar products having different modifiers
3. Open the receipt
4. See error

Expected behavior
The combined products should keeps original id of the products combined within, this will help Gastro pulling all modifiers attached to all those products.

Environment:

• NexoPOS 4.x: 5.0.0
• Gastro: 5.0.0