Remove implicit behaviors/tools in View-based diagrams

[pcdavid]

Currently, when a View-based diagram element (Node or Edge) does not specify any behavior for a given kind of tool (e.g. direct edit, delete, etc.), the runtime automatically provides a default one.
This is nice for quick startup, but it also means it is impossible to disable any of these tools, as even if the studio makers does not provide a tool, some behavior will be provided.

• The new rule will be that if a particular tool (for a given diagram element) is not explicitly present in the View model, the corresponding behavior should be simply disabled.
• When the user will create a new Node or Edge, in the same way as they currently get a default style element automatically created, they will get automatically configured tools for all the standard beahviors. These will be implemented thanks to Make the default/canonical tools' behavior callable from standard AQL expressions and/or operations #1562 and provide the same behavior as the current default, only explicitly visible in the view model.

[pcdavid]

org.eclipse.sirius.components.view.emf.diagram.ViewToolSectionsProvider will need to be updated not to provide tools (direct edit, delete from model) which are not explicitly configured in the View model. Except that in ViewToolSectionsProvider we do not have direct access to the actuel View model, only to the converted and "opaque" DiagramDescription & co.

[pcdavid]

We might need the work from #1422 to handle this.

[pcdavid]

We might need the work from #1422 to handle this.

There's a workaround. It's a bit of a kludge, but it will do until #1422 is done.