Fix DocumentsUI did not meet Google Accessibility Rating (GAR) criteria

To meet GAR criteria contrast ratio should at least 4.5:1
1.Fine tune ToolBar Icon and Text Color to full 100% white #FFFFFFFF
2.Modify ToolBar, Drawer header background and CheckBox color to #FF1A73E8
3.Enlarge TextSize of Dropdown sort component from 14sp(56px) to 18sp(72px)
4.Enlarge arrow icon from 36dp to 48dp

Bug: 79710817
Test: atest DocumentsUITests
Change-Id: I60ec0888fb793142f0974647c5e43b0a07bf6080