Rework color names

[mstruebing]

As addressed here: #1169

We should rework the current color names.
Color names are defined here: https://github.com/neos/brand/blob/master/index.js

By doing this make sure to replace all hardcoded colors in the UI with constants.

[mhsdesign]

is this related? #3201

:root {
    /* ... */
    --fontsHeadings-CssWeight: 400;
    --fontsCopy-Family: "Noto Sans";
    --fontsCopy-Style: Regular;
    --fontsCopy-CssWeight: 400;
    --colors-PrimaryViolet: #26224C;
    --colors-PrimaryVioletHover: #342f5f;
    --colors-PrimaryBlue: #00ADEE;
    --colors-PrimaryBlueHover: #35c3f8;
    --colors-ContrastDarkest: #141414;
    --colors-ContrastDarker: #222;
    --colors-ContrastDark: #3f3f3f;
    --colors-ContrastNeutral: #323232;
    --colors-ContrastBright: #999;
    --colors-ContrastBrighter: #adadad;
    --colors-ContrastBrightest: #FFF;
    --colors-Success: #00a338;
    --colors-SuccessHover: #0bb344;
    --colors-Warn: #ff8700;
    --colors-WarnHover: #fda23d;
    --colors-Error: #ff460d;
    --colors-ErrorHover: #ff6a3c;
    --colors-UncheckedCheckboxTick: #5B5B5B;
}