Feature request: adjust grey color in palette to support Button, Badge, etc

[shdq]

Initially, grey color in the theme was introduced for the Card and TextInput components.

Adjusting grey color to other colors will let to use it for components like Button and Badge.

Current shades of grey are: 000, 300, 400, 500, and 700.
Other colors have shades: 000, 100, 400, 500, and 600.

Required changes

For grey color shift overlapping shades used in other colors to vacant numbers. Add new shades and adjust Card and TextInput component shades. Some shades may be reused.

Changes should be done to both grey and darkGrey palettes.

Steps:

• Introduce new shades for grey and darkGrey as in other colors
• Adjust Card and TextInput color with new shades
• Add grey color for Button and Badge
• Update docs
• Add unit tests