HDRP: re-enable shadow mask menu of main window

com.unity.render-pipelines.high-definition/HDRP/RenderPipeline/SceneViewDrawMode.cs

             cameraMode.drawMode == DrawCameraMode.DeferredNormal ||
             cameraMode.drawMode == DrawCameraMode.ValidateAlbedo ||
             cameraMode.drawMode == DrawCameraMode.ValidateMetalSpecular ||
-            cameraMode.drawMode == DrawCameraMode.ShadowMasks ||
             cameraMode.drawMode == DrawCameraMode.LightOverlap
             )
             return false;