Roles Management v1

### Backend

- New controller is created called `RolesController` under the route `<URL>/api/admin/roles`
- Expose GET and POST endpoints.
- In the controller utilize the role management from `Microsoft.AspNetCore.Identity` as `RoleManager<DappiRole>`


### Frontend 
Under the page on route "Tab>User Administration" create a new page that contains a typical table with add and edit options