User interface for managing argument graphs in a project

[tfgordon]

On project pages, add user interface elements for managing the argument graphs of the project:

• listing existing argument graphs
• selecting an argument graph, navigating to the argument graph page, for example by clicking on a hyperlink.
• creating a new argument graph
• deleting argument graphs

Commands for editing and deleting argument graphs can be on the argument graph page, rather than the project page.

Commands for importing and exporting arguments are in a separate issue.

[sekaiser]

further discussion needed. implementing this feature involves a heavy rewrite of routing logic in the rest api and frontend.

[pallix]

I confirm that "listing existing argument graphs" requires a heavy rewrite of all most all routes. Not doable for M2.

[pallix]

The path should probably be something like /:pid/ags/:ag and not use the ':db' parameter anymore as it is not precise enough (there are different kind of databases (schema) in the project)