Suggest custom chains and scripts in Designer actions

In Designer, when creating an action the operation field only suggests default operations.

TODO

• Add suggestion for custom operations and scripts created in modeler
  • In actions
  • And operations when using the nuxeo-operation-button element

ACCEPTANCE CRITERIA

• After creating a custom chain in modeler, when typing its name the chain is suggested in the operation field of a Designer action and in the operation field of a Designer operation using a nuxeo-operation-button element
• After creating a custom script in modeler, when typing its name it is suggested in the operation field of a Designer action and in the operation field of a Designer operation using a nuxeo-operation-button element