To use existing Roles Iam Roles while enabling Amplify Studio.

### Describe the feature you'd like to request

To be able to use existing roles as authRole, Full- Access and Manage Role, when enabling studio

### Describe your use case and how the feature would improve your experience.

As a Security Best Practice when restricting IAM permission to users, for example using [PowerUserAccess](https://docs.aws.amazon.com/aws-managed-policy/latest/reference/PowerUserAccess.html) policy, we will not be able to create roles and hence cannot enable Studio.

### Describe alternatives you've considered

NA

### Additional context

FR when using CLI : [9733](https://github.com/aws-amplify/amplify-cli/issues/9733)
Submitting this request for Amplify Studio also.

Start by reading the linked Amplify CLI issue 9733 and tracing how Amplify Studio is enabled. Determine where authRole, Full-Access, and Manage Role are selected or created, then verify that enabling Studio can accept existing IAM roles without requiring new role creation.

Written by the indexing model from the issue text.