Upon installing a new Activity module (aka plugin), Block or Filter, upon visiting the Notification page, one arrives on a Plugins check page with 3 tables, as described in the online notice:
The following tables show the modules, blocks and filters that have been detected in your current Moodle installation.
Any 3rd-party plugin shows in the appropriate table, with a "Non-standard" label in the Status column. That is quite helpful.
It's a pity that when installing a new question type nothing shows in those tables.
Joseph