Don't apply the "dim wallpaper" effect if wallpaper is not supported

On auto, getSystemService(WallpaperManager) returns a non-null but non-working service (DisabledWallpaperManager) that fails on each method call (this seems like a rather unusual pattern). We detect this by calling isWallpaperSupported() and, if false, we won't try to apply the effect.

Bug: 327485783
Test: atest DefaultDeviceEffectsApplierTest
Change-Id: I1be7c902f4ae63d0b6191d9fcb106691052cbc55