add UI to generate a scenario.properties files from an abs with Assets

Should help designing in the early phases: a button that automatically generates an empty scenario file with all attributes and references

to simplify the work, we can:

• generate a comment to indicate when the attribute/reference accepts multiple values
• generate a commented line when there is no known default value for the attribute/reference

Ideally, multiple calls to this generator should increment the number at the end of the scenario file name (or add a page to ask for the file name)