Remove progress meter mixin and move code to the fylr theme

Author: elementalhub

src/scss/themes/fylr/_mixins.scss

@@ -18,5 +18,4 @@
 @import 'mixins/_checkbox';
 @import 'mixins/_list-view';
 @import 'mixins/_layer';
-@import 'mixins/_progress-meter';
 @import 'mixins/_toolbar';