[Feature Request] Make the theme colorpalette customizable

[Von-Birne]

I like to use lichess with a purple board and do not like the green highlighting of fields when moving a piece.

Therefor changed this as well as the blue highlight color for links and navigation with local css but I figured other people would enjoy their own colors as well.

Having another setting in the profile drop down might be nice. I could also imagine having a dedicated theme setting page with all sorts of options.

Here is an example of my landingpage:

[jalpp]

There are many extensions that make this possible by changing the move colour background themes etc, I believe there is also option to change colour of lichess logo and other properties. You can go here https://lichess.org/page/extend Under styles many extensions can be found.

[ddugovic]

Lichess could maybe review what Lishogi has done