Allow POI creation in Event form via popup

[timobrembeck]

Motivation

When a POI is created via the Event form, a new tab opens with the POI form, which might be unexpected for the users.

Proposed Solution

Instead of opening a new tab when a POI is created via the Event form, we could open a popup similar to the media library. The rendering process as well as saving the form should happen via ajax.

Alternatives

Additional Context