New avatar styles

[juliusknorr]

• Figure out a way to regenerate avatars
• New style based on lighter color palette https://github.com/nextcloud/server/blob/368f83095d443c28b0d90d2308549349cc28dd05/lib/private/Avatar/Avatar.php
• Clarify about contacts which uses the same color palette iirc?

The mockup:

The values would basically be the current avatar colors, but:

• The dark background color used as the text color instead
• a 10% light version of the color (much like primary-light) as the text color

@CarlSchwan also posted a nice article somewhere on accessible color combinations for tags somewhere, as a future step we could adapt that too.

[CarlSchwan]

#33752