Sable Dupe fix

Sable Dupe Fix
Fixes a duplication bug in Sable when assembling non‑Clearable containers (e.g. Create’s Table Cloth, Depot, Belt).

What is the bug?

In SubLevelAssemblyHelper.moveBlocks, Sable checks:

if (blockEntity instanceof Clearable clearable) {
    clearable.clearContent();   // standard containers: clear items at the old position
}

Some third‑party containers (like Create’s Table Cloth, Depot, Belt) do not implement Clearable.
As a result, the items in the old position are not cleared, while the new position loads a duplicate copy via loadWithComponents(tag, ...).
This causes the item count to double.

How the fix works

A lightweight Mixin is injected into SubLevelAssemblyHelper.moveBlocks:

• When the blockEntity is not an instance of Clearable,
  the tag is reset to contain only the id field plus coordinate fields.

• Then loadWithComponents(tag, ...) loads the container at the new position in a factory‑fresh state – with no items.

Compatibility

• Minecraft 1.21.1

• NeoForge 21.1.219+

• Sable 1.2.2+