[Feat]: Allow custom theme colors

[theopfr]

Description

This probably already got brought up but I didn't find anything related. It would be nice if we could set some custom colors so that the cookie consent fits better into different websites designs.

Proposed solution

Something in the lines of:

guiOptions: {
    colorTheme: {
        primaryColor: '#XXXXXX',
        primaryColorHover: '#XXXXXX',
        secondaryColor: '#XXXXXX',
        secondaryColorHover: '#XXXXXX',
        surfaceColor: '#XXXXXX',
        surfaceColorHover: '#XXXXXX',
    },
    consentModal: {
        position: 'bottom left',
        equalWeightButtons: false,
        flipButtons: false
    },
    preferencesModal: {
        layout: 'box',
        equalWeightButtons: false,
        flipButtons: false
    }
},

Or maybe just primaryButton and secondaryButton would be enough.

Additional details

No response

[orestbida]

This is already possible, but via css-variables.