Unify add to agenda option for motion, assignment and motion block

Current behavior
If you add a motion/assignement or motion block to the agenda (via the detail view and the three dot menu) the object is added at the end of an agenda

And assignments cannot be added via multi-select

And a motion via the multi-select the visiblity cannot be decided what the visibility is

Wanted behavior

• The following objects should hav a "add to Agenda" option in the the three dot menu
  • motion-detail
  • motion-list multi-select
  • assignment detail
  • assignment-list mullltiselect
  • motion blcok detail
• This option should open a dialog
• The dialog should have the following things inside of itself:
  • Title:
    • In detail view: "[title in detail view]: move to agenda"
    • in Multi: "Move all selected items to agenda"
  • The agenda visibility combox box
  • A "Parent agenda item" Combobox where you can select every item in the agenda

Additional context
inspired by https://github.com/OpenSlides/openslides-client/issues/2147

Start by tracing the motion, assignment, and motion block detail views and list multi-select actions related to adding items to an agenda. Compare the existing add-to-agenda behavior with the requested dialog, including visibility and parent agenda item selection; done means all listed entry points use the unified option and dialog.