Change notify icon color on enabled or disabled core (proxy)

[Lavshyak]

for https://github.com/InvisibleManVPN/InvisibleMan-XRayClient/issues/141

[Lavshyak]

Tremble! (I tested this only on master branch, not on develop)

[Lavshyak]

maybe it makes sense to make a gray icon instead of red and see how it looks