feat: add Forms management commands

[developerkunal]

🔧 Changes

Add first-class Auth0 Forms management to the CLI:

• Add forms list, show, create, update, delete, open, export, and import.
• Support interactive prompts, JSON/CSV output, file input, piped stdin, and non-interactive automation.
• Make interactive creation lightweight:
  • auth0 forms create prompts for a name and creates a minimal scaffold.
  • auth0 forms create --edit opens the complete JSON body in an editor.
  • auth0 forms create --example prints an embedded example suitable for --file.
• Open Forms directly in the Auth0 Dashboard builder with forms open.

Additional updates:

• Require --force for Forms deletion in agent mode.
• Add the required Forms Management API scopes.

🔬 Testing

• Unit tests and vet.
• Live Forms integration suite: 17/17 passed.
• Verified integration resources are cleaned up.

📝 Checklist

• Functionality is covered by tests.
• Documentation has been added.