[2D][Tilemap] Palette window's Active Tilemap still shows Tilemap which is disabled in sceneview

Palette window's Active Tilemap still shows Tilemap which is disabled in sceneview
Also applies to Grid when it is disabled

Repro steps:
- Click on Tilemap object in SampleScene
- Observe Active Tilemap in palette window shows "Tilemap" selection
- Use Brush tool and attempt to paint in Tilemap object
- Enable Tilemap and observe tiles are painted even when Tilemap is disabled

Expected result: Active Tilemap should show Nothing if all tilemaps in scene is disabled
Actual result: Active Tilemap still shows the last tilemap to be disabled