Improve "change your own delegation" menu

Current behavior
Currently the menu "Change your own delegation" is always visible when you can update/manage participants even if vote delegation is not activated. It is also visible if you have the permission "Can edit own delegation" and vote delegation is not activated.
Both scenarios are irritating.

Additionally, the placement of the menu itself is not great and should move to the user menu.

Wanted behavior

• The menu "change your delegation" should only be visible to a user if vote delegations is activated in the settings and the user has the permission "Can edit own delegation" #6141
• The menu should move to the user menu in the tool bar. It should be place below the presence state. The same icon and name could be used. #6141
• The dialogue to change your own delegation should change:
  • The dialogue should only contain the fields to change your delegation, the other three fields (group, structure level, participant number) should be removed completely not only greyed out. #6141
  • The title of the dialogue should change to "Edit your own delegation" #6141
  • Add a helptext to principals field: "You can only delete delegations you have received." #6141