Request FTP and SSH credentials when needed during shiny updates

This is a restoration of [31749] which was reverted in [31755].

It includes a number of enhancements from the original version.  Namely:
 * Not doing a credential check in src/wp-includes/script-loader.php
 * Add new function `wp_print_request_filesystem_credentials_modal`
 * update the version number in the list table when a plugin is updated

UI still needs further work, but this basic version should enable more testing

Props ericlewis, jorbin
See #31528



git-svn-id: https://develop.svn.wordpress.org/trunk@31811 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/plugins.php

@@ -476,4 +476,6 @@ do_action( 'pre_current_active_plugins', $plugins['all'] );
 </div>
 
 <?php
+wp_print_request_filesystem_credentials_modal();
+
 include(ABSPATH . 'wp-admin/admin-footer.php');