UWMOODLE-1231 Release session lock

Release session lock when querying user's courses across UW Moodle
sites.  This will prevent a slow remote site from locking-up moodle.

getcourses.php

@@ -38,6 +38,8 @@ $response->message = 'invalidrequest';
 
 $PAGE->set_context(context_system::instance());
 
+// Unlock session during potentially long webservice requests.
+\core\session\manager::write_close();
 
 if(confirm_sesskey()) {