Patch: Notifications color following ambience

SFOS 4.x introduced redesigned notification previews that are extremely bright and do not fit into the ambience.

This patch makes the previews use much darker ambience colors in dark ambiences, and appropriate colors in light ambiences.

Sources: https://github.com/ichthyosaurus/sailfish-public-patch-sources

Discussion: https://forum.sailfishos.org/t/patches-by-ichthyosaurus

Donations: https://liberapay.com/ichthyosaurus