Add 'minimize to system tray' toggle

[Woife5]

This pull request...

• [ ] Fixes a bug
• [x] Introduces a new feature
• [ ] Improves an existing feature
• [ ] Boosts code quality or performance

Description

This pr adds an option pannel to the GUI, which allows users to minimize the window to the system tray instead of the taskbar. It also adds a 16px * 16px icon which is displayed in the system tray so that a user can quickly identify the running bot.

Relevant Issue(s)

This PR closes issue #1325