Add missing doc blocks to wp-admin/includes/*.

Fix some egregious uses of tabbing.
Some functions can simply return `apply_filters(...)` instead of setting a variable that is immediately returned.

See #32444.


git-svn-id: https://develop.svn.wordpress.org/trunk@32654 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/plugins.php

@@ -148,6 +148,9 @@ if ( $action ) {
 
 			@ini_set('display_errors', true); //Ensure that Fatal errors are displayed.
 			// Go back to "sandbox" scope so we get the same errors as before
+			/**
+			 * @param string $plugin
+			 */
 			function plugin_sandbox_scrape( $plugin ) {
 				wp_register_plugin_realpath( WP_PLUGIN_DIR . '/' . $plugin );
 				include( WP_PLUGIN_DIR . '/' . $plugin );