Add Cypress tests to check diagram functionalities

Add Cypress tests to tests functionalities on diagrams :

• edge creation
• edge deletion
• edge renamed
• edge semantic Drag&Drop
• node (top nodes or sub nodes) creation
• node (top nodes or sub nodes) deletion
• node (top nodes or sub nodes) renamed
• node (top nodes or sub nodes) semantic Drag&Drop
• custom nodes
• custom tools
• graphical Drag&Drop