Multiple Context menus

[FelixJoehnk]

Hy, i am currently working on implementing a context menu for a specifiic type of Model.
The problem for future additions: one might want to have multiple context menues each assigned to a specific type of model. Since those might have different syntaxes.

One way of achiving this would be to have a symbol for every model type. This symbol than could be stored in the SModelRoot. Than we could simply use said symbol while calling "menuService = await this.contextMenuService();" in the mouse-listener since we have access to the SModelElement anyway.

Best Regards Felix