Themes: Add status bar and navigation bar to ThemesContract

Change-Id: I8048c735d7bbbfdb86ee5923b95bece6b4252bf7
Themes: Add previews to the themes contract.

Change-Id: I607a6eda1c63a701516d2bc78ca6b705841fbdf7
Themes: Add icon previews to ThemesContract

Credit to @BigBrother1984 for the original cherry pick

Change-Id: Icbfbee3404702a29881ad4933721d8beb39bef30
Themes: Style, boot animation, and wallpaper previews

Change-Id: I2b367bf5336c03f2a4972a05b68922065cd4a701