Blender Git Loki

T90372: Assets: When dropping material use active material slot.

Currently when dropping an asset the first material slot is always updated.
This patch changes that logic to update the active material slot.

In future the behavior will be updated to use the material slot of the face under the cursor.
That requires better feedback tot he user.

Reviewed By: Severin

Maniphest Tasks: T90372

Differential Revision: https://developer.blender.org/D12056