Allow create dynamic tokens with TTL for the SA used for SSO+RBAC

[keymon]

Summary

A security review in our project flagged the static secret created for SSO.

When setting SSO, we read a static token of a Service Account, with no TTL.

argo-workflows/server/auth/gatekeeper.go

Lines 320 to 326 in f470fda

	func (s *gatekeeper) authorizationForServiceAccount(ctx context.Context, serviceAccount *corev1.ServiceAccount) (string, error) {
	secretName := secrets.TokenNameForServiceAccount(serviceAccount)
	secret, err := s.cache.GetSecret(ctx, serviceAccount.GetNamespace(), secretName)
	if err != nil {
	return "", fmt.Errorf("failed to get service account secret: %w", err)
	}
	return "Bearer " + string(secret.Data["token"]), nil

But ideally, we should instead use corev1.TokenRequestSpec.

I think something like

        // Define the token TTL
	tokenTTL := int64(3600) // 1 hour

	// Create the TokenRequest API client
	tokenRequestClient := s.k8sClient.CoreV1().ServiceAccounts(serviceAccount.Namespace)

	// Create a TokenRequest object
	tokenRequest := &corev1.TokenRequest{
		Spec: corev1.TokenRequestSpec{
			Audiences: []string{"https://kubernetes.default.svc/"}, // Adjust based on your use case
			ExpirationSeconds: &tokenTTL,
		},
	}

	// Request the token
	tokenResponse, err := tokenRequestClient.CreateToken(ctx, serviceAccount.Name, tokenRequest, metav1.CreateOptions{})
	```

## Use Cases

When using SSO with RBAC. This prevents create a static secret.
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