Accessibility: Administration: Update various background colors for increased contrast.

This ensures that contrast between text color and background meets the WCAG 2.0 AA recommended value. The following locations were changed:

- Network List Tables: Use lighter background colors for site status indicator.
- Nav Menus: Use a lighter background color for invalid menu items.
- Pointers: Use a darker background for pointer header.
- Themes: Use darker background on filter button hover.
- Customizer: Use darker background for selected widget.

Follow-up to [50025], [50571].
Props kebbet, melchoyce, peterwilsoncc.
Fixes #52760.


Built from https://develop.svn.wordpress.org/trunk@50687


git-svn-id: http://core.svn.wordpress.org/trunk@50296 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50686';
+$wp_version = '5.8-alpha-50687';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.