Fix PR review comments on SCIM surfaces

- Return valid JSON (null) in `prb scim view --json` when no
  SCIM configuration exists
- Remove organization ID from MCP not-found error to prevent
  identifier disclosure in multi-tenant paths
- Use nullable GID refs for bridge_id and connector_id in
  MCP specification for correct generated ID typing

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/cmd/scim/view/view.go

@@ -149,6 +149,9 @@ func NewCmdView(f *cmdutil.Factory) *cobra.Command {
 			}
 
 			if resp.Node.ScimConfiguration == nil {
+				if *flagOutput == cmdutil.OutputJSON {
+					return cmdutil.PrintJSON(f.IOStreams.Out, nil)
+				}
 				_, _ = fmt.Fprintln(f.IOStreams.Out, "No SCIM configuration found.")
 				return nil
 			}