Save themed icon switch's chcked state in savedInstanceState am: 3f62f8a220 am: 68e31b78af

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/15153295

Change-Id: Ia7a9024d9fec83bd4b1de0461508ae6c24b7ba24