Upgrade/Install: Display plugin and theme update counts on WordPress Updates screen.

This restores the information that was previously included in a title attribute tooltip on pending updates link in the toolbar.

Follow-up to [50801].

Props sabernhardt, audrasjb, mukesh27, davidbaumwald.
Fixes #53031.

git-svn-id: https://develop.svn.wordpress.org/trunk@50803 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/update-core.php

@@ -449,8 +449,18 @@ function list_plugin_updates() {
 	} else {
 		$core_update_version = $core_updates[0]->current;
 	}
+
+	$plugins_count = count( $plugins );
 	?>
-<h2><?php _e( 'Plugins' ); ?></h2>
+<h2>
+	<?php
+	printf(
+		'%s <span class="count">(%d)</span>',
+		__( 'Plugins' ),
+		number_format_i18n( $plugins_count )
+	);
+	?>
+</h2>
 <p><?php _e( 'The following plugins have new versions available. Check the ones you want to update and then click &#8220;Update Plugins&#8221;.' ); ?></p>
 <form method="post" action="<?php echo esc_url( $form_action ); ?>" name="upgrade-plugins" class="upgrade">
 	<?php wp_nonce_field( 'upgrade-core' ); ?>
@@ -602,8 +612,18 @@ function list_theme_updates() {
 	}
 
 	$form_action = 'update-core.php?action=do-theme-upgrade';
+
+	$themes_count = count( $themes );
 	?>
-<h2><?php _e( 'Themes' ); ?></h2>
+<h2>
+	<?php
+	printf(
+		'%s <span class="count">(%d)</span>',
+		__( 'Themes' ),
+		number_format_i18n( $themes_count )
+	);
+	?>
+</h2>
 <p><?php _e( 'The following themes have new versions available. Check the ones you want to update and then click &#8220;Update Themes&#8221;.' ); ?></p>
 <p>
 	<?php