Co-authorship enhancement on Initiatives

Distinguish promoting committee rights from the author of the initiative ones: - The co-authors of an initiative can't revoke the original author - The co-authors of an initiative can't revoke other co-authors - Co-authors can't accept or refuse another co-author - Co-authors can't send the initiative to technical validation - Original author must always appear first on the FO authors list Co-authorship display on the initiative FO page - Collapse co-authorship list in the case of more than 3 authors (like for endorsements)