On some pages we have a splitted layout for which we use `Primer::Alpha::Layout`, e.g.

* Meetings Begin of the insertion

End of the insertion Begin of the deletion
End of the deletion * Storages Begin of the insertion


End of the insertion Begin of the deletion

End of the deletion For the right side pane (called Begin of the insertion`Sidepanel`),End of the insertion Begin of the deletion `Sidebar`),End of the deletion I want a fixed component which can be re-used so that all right panes look the same

### Acceptance criteria

* [ ] Create a Sidebar component
* [ ] Provide slots for individual secions with
* [ ] a header
* [ ] an action button
* [ ] some content
* [ ] Use the `Primer::OpenProject::BorderGrid` internally

#### Hint for QA

* This will be implemented completely inside the primer\_view\_components repo, and this needs to be tested inside the lookbook (or in core after it was updated there, which will be probably be a separate ticket).