[DMN Designer] Export to SVG requirements

There was some talk of being able to export DMN diagrams to SVG a few months ago (IIRC mmortari@redhat.com was first to start the discussion). The linked JIRA will provide the ability to export the "graph" to SVG however we should define the requirement as a whole for DMN. Various options exist:

• Export from the "graph" screen exports the graph and all node definitions (i.e. table dumps)
• Export from the "graph" just exports the graph. Users would need to to each node definition to export the individual tables.
• Export shows a dialogue listing the parts of the diagram from which the User can select components to export).

This JIRA is to mainly capture the incomplete state of "Export to SVG" for DMN.