Update widget manipulation colors to match AOD.

This CL makes two changes:
1. Changes the colors we use from system_accent1_50 ->
system_accent1_100 (light wallpapers) and system_accent2_700 ->
system_accent2_600 (dark wallpapers).
2. Changes when we use the light/dark colors. Before: light accent color
when wallpaper luminosity < 0.3. After: light accent color when wallpaper luminosity < 0.7.

Bug: 192359286
Test: manual on light/dark wallpapers with light/dark theme
Change-Id: I28abfd77439a16b4bb637376fd88180d536364cf
Merged-In: I28abfd77439a16b4bb637376fd88180d536364cf