[icon] redrawn icon pack based on SF Symbols

[redbreast]

Hi Calibre community,
Inspired by utterances's “San Francisco" icon pack, I created an new icon pack for MacOS based on SF Symbols.

Features:

• a lot of redrawn icons based on the actual functions in Calibre
• more suitable size, weight and color
• reduce the use of color for a more modern looking
• ready for light and dark mode
• a prepared color setting for importing
• color system: Green - OK/Add/ON/Unlocked, Red - No/Back/Exit/Minus/Locked, Orange - Attention/Coloured, Blue - Info, Purple - Edit/Code, Yellow - the rests.

Some SF Symbols are included, they are licensed for used on Apple platforms and non-commercial use. The rest icons I drawn are also Creative Commons (CC BY-NC).

The icon pack file and thumbnails will be posted in 2nd floor.