Support Rocky Linux

[byte]

Galera Manager on Rocky Linux 8 would be nice; there has been a user requirement for this. Maybe don't let it fail on OS check, best effort basis?

[root@rocky ~]# cat /etc/redhat-release
Rocky Linux release 9.2 (Blue Onyx)
[root@rocky ~]# ./gm-installer install
INFO[0000] OS Detected: RedHat / Rocky Linux / Linux / Blue Onyx / 9.2
Unsupported OS!
Supported OSes:
centos:7: deprecated
debian:10: deprecated
debian:11: active
redhat:8: active
ubuntu:18.04: deprecated
ubuntu:20.04: active
ubuntu:22.04: active

[byte]

Requested again at webinar, 8, and 9

[jybleau]

And AlmaLinux