Support for Cloning existing Roles across DBs

[ganderaj]

Describe the feature:
At the moment, Attu supports creating users and roles and associating roles to users. Feature request is to provide Attu Admins ability to clone existing role from DB-A to DB-B thereby avoiding the laborious activity to recreate role again on new DB.

Describe a specific use case for the feature:
Since Roles are under the scope of "database", a role needs to have "grants" explicitly setup across various databases to provide consistent privileges.

An existing user on DEV DB requests access on PRD DB. For consistency, Admin has to refer to his "Role" and manually recreate similar Role on PRD DB. Cloning Roles would be of great help.