NotificationAPI: Dark mode support for icons

[AgentConDier]

Previously, the black notification icons were shown on a dark background if system-wide dark mode was enabled. (At least in some cases, there are differences between vendors and android versions) To make them more visible, apply a white tint while termux is in dark mode.

The second commit fixes an issue I had with the latest build from GH Actions (df3cb50) where the first notification action supplied after a reboot overwrote all subsequent ones.

Tested on a Huawei Mate 20 Pro with Android 10 EMUI 12 Termux 0.118.0+1488bb0