feat: use monochrome tray icon and fix tray icon on macOS (Fixes #88)

[sussycatgirl]

Please make sure to check the following tasks before opening and submitting a PR

• [x] I understand and have followed the contribution guide
• [x] I have tested my changes locally and they are working as intended
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Replaces the tray icon with a monochrome one, and includes special:tm: icons specifically for macOS, which apparently has special requirements in order to display them properly (https://stackoverflow.com/questions/41664208/electron-tray-icon-change-depending-on-dark-theme/41998326#41998326).

[sussycatgirl]

referencing issues in PR title doesn't work? do your thing github

fixes #88

[sussycatgirl]

nvm

[0xCUB3]

Please implement this guys :)