Hard-delete workspaces

[JAORMX]

After doing #668 we should also add the ability to finally hard-delete a workspace.

That is, we nee to add the ON DELETE CASCADE constructs in the database for each foreign key that references a workspace.

We should also have a CRUD method to hard-delete an archived workspace.

This should encompass both the REST API and the pseudo-CLI.

[aponcedeleonch]

Closed by: #686