Icu 13880 create manage scopes route and view with keyword values (#2342)

* feat: 🎸 manage scopes route and page

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-13880

* Update addons/core/translations/resources/en-us.yaml

Co-authored-by: Zhihe Li <zhihe.li@hashicorp.com>

* Update ui/admin/app/abilities/role.js

Co-authored-by: Zhihe Li <zhihe.li@hashicorp.com>

* Update ui/admin/app/components/form/role/manage-scopes/index.hbs

Co-authored-by: Zhihe Li <zhihe.li@hashicorp.com>
---------

Co-authored-by: Zhihe Li <zhihe.li@hashicorp.com>

addons/api/addon/generated/models/role.js

@@ -23,6 +23,7 @@ export default class GeneratedRoleModel extends BaseModel {
   description;
 
   @attr('array', {
+    emptyArrayIfMissing: true,
     description:
       "The scopes to which this role applies.  Defaults to the role's scope.",
   })