Move app.scss into App.vue

Signed-off-by: Joas Schilling <coding@schilljs.com>

css/app.scss

@@ -1,10 +0,0 @@
-// Rules for the App.css entry point
-
-body {
-	overflow: hidden;
-}
-
-/* FIXME: remove after https://github.com/nextcloud/nextcloud-vue/issues/2097 is solved */
-.mx-datepicker-main.mx-datepicker-popup {
-	z-index: 10001 !important;
-}

css/merged.scss

@@ -1,2 +1 @@
 @import './icons';
-@import './app';