Feat: Create Unicorn Icon theme

[ajstrongdev]

Quite a large task. We need a unified Icon theme for Rhino Linux.

Specification:

• Must have a border gradient that pulls from the primary colours of the icon
• Must have a darkened background gradient that pulls from colours utilised on the border.
• Must have a candy designed icon in the centre
• Must be rounded squircles, similar to icons found in macOS Big Sur+

[JanluOfficial]

• Gradient is based on the icons colors
• The darkened background is done by setting the inner frames color to #000000 at 70% opacity.
• The candy effect has been scrapped as flat design looks and works better, aswell as being easier to make.
• Border Radius is 1/4th of the width/height.

[ajstrongdev]

Assigning: @rudy-in