We can now create placeholder Cards by inputting [[some placeholder name]] inside a Card.
Current behaviour: When creating a link to a placeholder card, after clicking on it, the new card gets created. Other references to that same placeholder (within the same note) are not created. Clicking other placeholders creates another new card with the same name/content.
Requested behaviour: All other references with the same name are updated to point towards the new Card, automatically or after a confirmation dialog.