Support Dark/Light Theme for DocumentsUI (1/N)

Define Light Theme and ToolBarTheme to match M2 design
Apply M2 Light color for StatusBar / ToolBar
Remove "*android" private reference to achieven unbundle
Refer GM Color Palettes(Neutral)

Bug: 112316733
Test: atest DocusmentsUI
Change-Id: I3b82dbd3e64be5c919615ca1610d275d518f4510