MDL-63580 core_task: Deprecation CLI scripts from admin/tool/task/cli

Copy the CLI scripts from admin/tool/task/cli to admin/cli (schedule_task.php and adhoc_task.php)
and rename to scheduled_task.php and to improve in order to use cron_run_inner_scheduled_task.

admin/tool/task/cli/schedule_task.php

@@ -17,6 +17,9 @@
 /**
  * CLI task execution.
  *
+ * @deprecated since Moodle 3.9 MDL-63580. Please use the admin/cli/schedule_task.php.
+ * @todo final deprecation. To be removed in Moodle 4.3 MDL-63594.
+ *
  * @package    tool_task
  * @copyright  2014 Petr Skoda
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
@@ -33,6 +36,8 @@ list($options, $unrecognized) = cli_get_params(
     array('h' => 'help')
 );
 
+debugging('admin/tool/task/cli/schedule_task.php is deprecated. Please use admin/cli/scheduled_task.php instead.', DEBUG_DEVELOPER);
+
 if ($unrecognized) {
     $unrecognized = implode("\n  ", $unrecognized);
     cli_error(get_string('cliunknowoption', 'admin', $unrecognized));
@@ -65,6 +70,7 @@ if ($options['showdebugging']) {
 if ($options['showsql']) {
     $DB->set_debug(true);
 }
+
 if ($options['list']) {
     cli_heading("List of scheduled tasks ($CFG->wwwroot)");