Setup Wizard: add / edit different sections (e.g. related notes) and tabs

[sleidig]

follow up task of #2047 , #2057

Implement the stub ConfigEntityPanelComponent

• flag components that support to be displayed in a entity-details view somehow, so that we can query a list of all of these from the registry
• use that to build a simple UI that allows to select from these components to add a new section + filter it based on the references the current entity has in its schema
• use dynamic components and avoid a long ngIf cascade in the template for selecting the right admin-component - and treat FormComponent as just one of them
• add a simple config form to configure details of a component like related-entities-component