Revert "Revert "Eevee: support accessing custom mesh attributes""

This reverts commit e7fedf6dba5fe2ec39260943361915a6b2b8270a.

And also fix a compilation issue on windows.

Differential Revision: https://developer.blender.org/D12969

Fix drop of dimensionless objects in 3DView

The matrix and location were not being calculated in this case.

View3D Snap Cursor: don't limit the number of states

The benefit of a flat array in this case is small and limiting, so use a linklist.

View3D Snap Cursor: sanitize and increase the maximum amount of states

3 is a small amount as each viewport creates a gizmo that creates its own state

Now if the state is not created, the gizmos use the last state.

Cleanup: silence warnings

```
warning: assignment discards ?const? qualifier from pointer target
warning: declaration of ?co? shadows a parameter
```

UI Drag Drop: allow customizable drawing

No functional changes.

This commit adds 3 callbacks for `wmDropBox` which allow custom drawing
without affecting the internal dropbox API.

Differential Revision: https://developer.blender.org/D12948

Drag Drop: allow customizable drawing

Assets: Snapping with visual feedback while dragging

The drag and drop feature of objects in 3D View has been modified to include:
- Snap the object being dragged.
- Visual feedback through a box and the placement tool grid.

Maniphest Tasks: T90198

Differential Revision: https://developer.blender.org/D12912

Fix T92466: Crash snapping to text objects with XRay shading

Should have been addressed along with {rB6cff1d648030}

Fix errors in be171b295fc7d

´´´
error C4133: 'function': incompatible types - from 'float [2]' to 'int *'
error C4133: 'function': incompatible types - from 'const int [2]' to 'const float *'
´´´