Move Styles & wallpapers to the homepage group

- Add Styles & wallpapers to the homepage group.
- Create a new display settings xml for the silky home.
- Remove Styles & wallpapers from new display settings xml.
- Apply the RestrictedTopLevelPreference to remove the restricted icon.

Bug: 168166015
Bug: 174964139
Test: robotest & visual with turning on/off silky home
Change-Id: Ib495b39bc62413242247f7e767c0e44bacc6e937