Fallback to Client_id and secret flow if OAuth flow doesn't support Dynamic Client Registration (DCR)

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue
- [x] I have run `q doctor` in the affected terminal session
- [x] I have run `q restart` and replicated the issue again

### Operating system

macOS 15.6.1 (24G90)

### Expected behaviour

If an authorization server doesn't support DCR, Q CLI should fallback to using client_id and client_secret to complete OAuth Flow

### Actual behaviour

Authorization URL returned as part of OAuth flow is invalid

### Steps to reproduce

_No response_