Introducing Site Icon, favicon management for WordPress.

This v1 marries Jetpack's Site Icon module with the Media Modal, reusing code
from the Custom Header admin. For now, the core-provided icons will be limited
to a favicon, an iOS app icon, and a Windows tile icon, leaving `.ico` support
and additional icons to plugins to add.

Props obenland, tyxla, flixos90, jancbeck, markjaquith, scruffian.
See #16434.



git-svn-id: https://develop.svn.wordpress.org/trunk@32994 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/template.php

@@ -1778,13 +1778,17 @@ function _media_states( $post ) {
 			$media_states[] = __( 'Background Image' );
 	}
 
+	if ( $post->ID == get_option( 'site_icon' ) ) {
+		$media_states[] = __( 'Site Icon' );
+	}
+
 	/**
 	 * Filter the default media display states for items in the Media list table.
 	 *
 	 * @since 3.2.0
 	 *
 	 * @param array $media_states An array of media states. Default 'Header Image',
-	 *                            'Background Image'.
+	 *                            'Background Image', 'Site Icon'.
 	 */
 	$media_states = apply_filters( 'display_media_states', $media_states );