Create a Pure GUI Role Editor

Let's fully hide the JSON and allow driving the role from a pure GUI. Let's also allow full editing at both add and edit time to unify things. People can choose to drop to JSON if they want, which follows the pattern we have elsewhere with table schemas, etc.

Start by locating the existing role add and edit UI, then compare it with the table-schema editor referenced in the issue to understand the established JSON and GUI pattern. Done means roles can be fully created and edited through the GUI at both stages, with JSON hidden by default but still optionally available.

Written by the indexing model from the issue text.