Currently we define our color palette in two places, both in class-loader.php for the editor and in _colors.scss for the theme, and there are differences between the two (especially for the grey colors). We need to harmonise this so that colors are the same in both backend and frontend. We should check with the design team to make sure which colors are the correct ones.

Also we can now use theme.json to set the palette, so we might as well do that at the same time and then we no longer need to define it in the blocks repo