[Evaluation] enhance resources evaluations

[Elorfin]

We want to expose evaluation information on the ResourceNode.
For now, evaluated resources use props defined on the AbstractResource, which make it unavailable outside the plugin itself.

ResourceNode should expose :

• evaluated flag. This will be used in Path to replace the step option.
• required flag. This is used by workspace evaluation to know which resource participate to the WS evaluation. For now this is stored on the ResourceUserEvaluation. It would be interesting to move it on the node to avoid generating empty ResourceUserEvaluation for all the users of the workspace (TODO : check the impact of this).
• score type. We will need to grab some logic from the quiz plugin which already implement this.

Current resources with evaluation :

• Quiz
• Dropzone
• Scorm