Move wallpaper local color extraction to background

This also moves all local color extraction related fields to the same
location, and remove unused parameters, in preparation for further refactors.

Test: treehugger
Test: perfetto trace
Test: atest WallpaperManagerTest
Bug: 268057764
Change-Id: I767889ae58d0132c987c5eda5519faf46150c67b
1 file changed