Backslot Mod 1.2.0-1.21.11

• Added support for Addons: implement "BackslotItem" in your item's class to have extra methods for interacting with the backslot!
• Items now run inventoryTick() when in the Backslot
• Revamped custom positioning system:
• you can now decide what body part the item should render on (options are: "body"(Default),"head","left_arm","right_arm","left_leg" and "right_leg") and if it should move when a item is equipped on your chest slot (only for "body")
• X Y and Z are now combined for scale position and rotation (see example image)