Add UI

[optimus-code]

Add a UI window to represent the LegacyFlavourConfig class settings.

• SVG icons for LegacyFlavour
• Checkboxes for bool properties
• Sliders for 0-1 decimal values
• Colour mode selector based on enum
• Add a tab for each colour mode
• Configure each mode tab to show colour pickers with labels for all the options,
• Utility/functional icon buttons for toggling bool functions like whiteness, custom zone colouring