Added a Nix Flake and support for running from the Nix Store (#47)

* Added a Nix Flake and support for running from the Nix Store

* Removed variable imports since they're brough in at the top level.

* Removed redundan imports and remove unused files (moved to temp).

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Co-authored-by: Jas Singh <jaskiratpal.singh@outlook.com>

scss/style/bar/media.scss

@@ -1,6 +1,3 @@
-@import "../colors";
-@import '../../variables';
-
 .bar-button-label.media {
   color: if($bar-buttons-monochrome, $bar-buttons-text, $bar-buttons-media-text);
   margin-left: $bar-buttons-media-spacing;