Merging ub-launcher3-qt-r1-dev, build 5691421

Test: Manual

Bug:135150283 P1 [Wallpaper] Investigate high RSS HWM in
Bug:135209029 P1 Update currently set wallpaper thumbnail to work with Micropaper wallpaper
Bug:135595582 P1 Log entry points for themepicker/wallpaper
Bug:135716309 P2 The downloaded contents are not placed in the downloaded area.