Support RHEL 9

This patch includes changes required to run devstack on RHEL 9.

- en_US.utf8 is provided by glibc-langpack-en
- iptables command is provided by iptables-nft
- Use /etc/os-release to identify the distro in RHEL 9 as it doesn't
  provide lsb_release command.
- CRB repository name is different from CentOS 9

Change-Id: I8f6d9263b24f9c2cf82e09258e2d14d7766ad337
diff --git a/stack.sh b/stack.sh
index ccd2d16..6e7b11a 100755
--- a/stack.sh
+++ b/stack.sh
@@ -391,7 +391,10 @@
     # Patch: https://github.com/rpm-software-management/dnf/pull/1448
     echo "[]" | sudo tee /var/cache/dnf/expired_repos.json
 elif [[ $DISTRO == "rhel9" ]]; then
+    # for CentOS Stream 9 repository
     sudo dnf config-manager --set-enabled crb
+    # for RHEL 9 repository
+    sudo dnf config-manager --set-enabled codeready-builder-for-rhel-9-x86_64-rpms
     # rabbitmq and other packages are provided by RDO repositories.
     _install_rdo