A first step to adding automatic dark mode color scheme switching. Adds a new SCSS file at `color_definitions.scss` that serves to output all SCSS color variables as CSS custom properties. And replaces all SCSS color variables with the new CSS custom properties throughout the stylesheets.
This is an alpha feature at this point, can only be enabled via console using the `default_dark_mode_color_scheme_id` site setting.
* UI: Mass grant a badge from the admin ui
* Send the uploaded CSV and badge ID to the backend
* Read the CSV and grant badge in batches
* UX: Communicate the result to the user
* Don't award if badge is disabled
* Create a 'send_notification' method to remove duplicated code, slightly shrink badge image. Replace router transition with href.
* Dynamically discover current route
