Add typing for essential services and events

[nikku]

Is your feature request related to a problem? Please describe.

As a follow-up to #2121 I'd like to expose essential services and events so that they are discoverable, out of the box.

Describe the solution you'd like

• For the stock modeler and viewer distributions expose essential services and events (TBD what these are)
• For extension use-cases allow default types to be overridden or extended

Describe alternatives you've considered

Make this a user land problem; we already provide the foundations via #2121.

Additional context

None.