Fixes#5168
- Added primaryInverted and primaryInvertedHover to design system.
- Changed primary button background with a gradient to inverted-flat for
both light and dark themes.
- Hover added to go lighter (consistent with tertiary color of +5 step
on GRAY_SCALE).
- Font color changed from primary to inverted.
- Modified button border from light to strong.
Two components are still utilizing the button with gradient background -
email and chrome extension.
Figma design guidelines show them to be inverted and flat (not
gradient).
- Should I change those as well?
- Should the gradient style be removed altogether after this has been
completed?
Co-authored-by: Henry Kim <henrykim@Henrys-iMac.local>