Create Mantine palette

[web-devel]

https://mantine.dev/
https://github.com/mantinedev/mantine

• Create demo-mantine project with a palette containing Mantine components. See https://github.com/react-buddy/demo-chakra-ui for example.
• Create mantine package in this repo

[web-devel]

• Remove unused imports and Popover from App.tsx
• AspectRatio component has wrong documentation link.
• Remove variants which are the same as default (e.g. Button - filled, ActionIcon - transparent)
• Checkbox - with color/Chip - with color - add checked state by default (to see what is color)
• Tabs - contentd ?
• Data display -> Data Display
• Progress and Divider previews do not work

[lovtsovaik]

see notes in doc