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_

Inizia eseguendo `q doctor` e `q restart`, quindi riproduci il flusso OAuth con un Authorization Server senza Dynamic Client Registration e controlla l’URL di autorizzazione restituita. Il lavoro è completato quando la CLI esegue il fallback al flusso client_id e client_secret e completa OAuth correttamente con un URL valido.

Scritto dal modello di indicizzazione a partire dal testo della issue.