Ability to define a preset color collection or palette

Thank you for the tip ! I had to set the palette this way in order to get it to work :
$element['#attached']['drupalSettings']['color_field']['color_field_widget_box']['settings'][$element['#uid']]['palette'] = $colors;

Hi, I've created a patch with the following features:

- Add a settings page to define the colors palette.
- Add a widget settings to allow entering a custom hex code on the box widget.
- Load the settings palette colors as default value when the field is configured of if the field settings value is empty.

Updated patch, the previous had a typo on a couple of filenames.

I am working here.