Sophisticated backpack button compat

[axtrough]

Checklist

• I am requesting a new feature or a functional improvement.
• I am not requesting an update or backport.
• This feature does not exist on the latest version.
• This feature has not already been requested.

Feature Description

Since the backpacks dont have their own menu, but instead kinda just expands your inventory menu. you cant really place the buttons where you want them. They just stay at the same place but the X is automatically offset to fit the "backpack" width.

It would be nice if they followed the player inventory so they would be positioned at the correct spot.

Video to show:
https://github.com/user-attachments/assets/f8cf9eb8-b027-40ec-8edc-7abb722f8c98

Use Case

It would allow for a more seemless experience when using these two mods together. It would greatly improve the look of the inventory when it all fits right. Personally I get really picky about these things that are "off", and I think others also share this mindset.

Minecraft Version (if not latest)

1.20.1

[NotRyken]

Unless/until someone comes up with a good way to account for inconsistent-width inventory menus this will not be considered.

[NotRyken]

[Note to self] one possible workaround would be to add a boolean to the class policy record to control whether the button position is calculated relative to the inventory menu edge (current) or the reference slot edge (new). The main issue is how to set up the config UI for that.