[DocsUI M3] Add drag hovered state for grid folders

Add the drag hovered state which matches the colours of
the hovered state. This state is for when an item is dragged
over a folder.

See bug for demo.

Bug: 355569425
Test: m DocumentsUIGoogle && manual inspection
Flag: com.android.documentsui.flags.use_material3
Change-Id: I3d58b499468316d5dea207f1f9ac1e6bba7c2b49