Merging ub-launcher3-qt-r1-dev, build 5759495

Test: Manual

Bug:137864652 P1 Do not use private resources in Wallpaper/Theme Picker
Bug:138404632 P1 When the current wallpaper is a motion photo, the style preview doesn't show a wallpaper
Bug:138446847 P2 TopLevelPickerActivity needs to be full screen
Bug:64712476 P3 Import translations for dev branches
Change-Id: If7825a04993a26823a445e9ee989dbf52fee6d88