### Context

For the split screen we have dedicated slots in the base.html.erb called `content_body`, `content_body_right` and `content_header` . When filled, the three parts look and behave as we want for split screen (including mobile) 
This was introduced for the new notification center split screen.

For full view pages like WorkPackages or the Documents full view, this layout however does not fit as it covers a completely different use case.

<br>

### Acceptance

This is the expected construct of these pages:

```text
|-------------------------------------------------
| | Tab1 | Tab 2 | ... |
| PageHeader | |
| | |
|---------------------------| |
| | |
| | |
| | some |
| some info | more |
| about the | details |
| object | |
| | |
| | |
|-------------------------------------------------
```

<br>

* Similar to the split screen, there is a possibility to fill certain slots which then behave for each full view in the same way

* The right side:

* goes full height

* is optionally resizable

* On mobile:

* The two parts merge into one. The TabNav is extended by a new entry at the first position which contains the former left side Begin of the insertion

* Ideally, we would be able to keep the existing routing behaviorEnd of the insertion