Can't select a group when creating a content list block and using the event content type

Problem/Motivation

I'm creating a new content list block using the layout builder. I want to select an "event content type" and also limit these event to a specific group. When trying to search for my group it never shows up in the autocomplete options.

Steps to reproduce

1. Enable social_event_content_block module.
2. Create a new flexible group
3. Create a new event that is part of the group created before
4. Go to block/add and select the Custom content list block
5. Select the 'Event' as Type of Content
6. In the "Groups" field try to search for the group created before
7. Group can't be found.

Proposed resolution

The issue is that the flexible group type is not set as an option to be referenced for this field, so we need to add it.

Remaining tasks

User interface changes

API changes

Data model changes