Integrate sidebar into navbar

[SunVal]

The navbar only consists only of Home button, darkmode toggle and fullscreen butten as of now. To reduce the number of menu elements the current sidebar shall be integrated into the navbar following a rework of it's structure.

The new navbar shall encompass the following items:

• Home
• File menu
  • New empty model
  • Save
  • Export options
  • Coloring
  • View
• Edit
  • Edit options
  • Discard Changes
  • Undo
  • Redo
• Collaboration
• Settings
  • Tutorial
  • Services
  • Levels and Children