Made a mass of accessibility improvements

- Changed default focus styles
- Updated dropdowns with keyboard navigation
- Updated modals with esc exiting
- Added accessibility attirbutes where needed
- Made many more elements focusable
- Updated hover effects of many items to also apply when focused within

Related to #1320 and #1198

resources/views/components/code-editor.blade.php

@@ -1,6 +1,6 @@
 <div id="code-editor">
     <div overlay ref="overlay" v-cloak @click="hide()">
-        <div class="popup-body" @click.stop>
+        <div class="popup-body" tabindex="-1" @click.stop>
 
             <div class="popup-header primary-background">
                 <div class="popup-title">{{ trans('components.code_editor') }}</div>