A dedicated space on the settings page to change the preffered themes

[alexis-opolka]

Related references:

• https://primer.style/foundations/color/overview
• https://primer.style/foundations/primitives/color
• https://primer.style/components/button
• https://primer.style/components/link

[alexis-opolka]

Space Added and nearly finished in https://github.com/alexis-opolka/alexis-opolka.github.io/commit/96a450dc80259b15e58a94478ccfebec2a045fa1 .

This lets to be done:

• [ ] Adding interactivity and taking into account the selected theme
• [ ] Transforming the dedicated space in the settings into a selection field