[DMN Designer] Included Models - Add the "Included Model dialog" to the "Included Models tab"

Create a new dialog for including external DMN models, considering the following mockup:

Sub-tasks:

• Add the button in the Included Models tab
• Update RecordEngine for the create action
• Create the Included Model dialog
• Add the assets dropdown (which must be re-usable in the test scenario) in the dialog