[FEAT] Add Dark theme support

[csouchet]

https://mui.com/material-ui/customization/dark-mode/#toggling-color-mode
https://mui.com/material-ui/react-switch/#customization
https://mui.com/material-ui/react-button-group/#button-variants
https://mui.com/material-ui/react-drawer/

https://zenoo.github.io/mui-theme-creator/

https://dev.to/hasone/how-to-add-dark-mode-in-gatsby-react-project-jml

[csouchet]

A POC was done: #1051 

From what I've seen, with the current version of Material UI, it's only possible to have 2 modes for the theme: light and dark.
It would have been cool to extend these modes to support different color-blind themes.