Add UBI9 Base Docker Image

Overview

A Docker image that uses Red Hat Universal Base Image 9 will be added.

There's nothing particularly noteworthy though...

Jpsonic latest is based on the small Alpine, which uses musl. Ubuntu was created as a libc-based platform for the purpose of comparing with Alpine.
- I don't think the end result will be much different 🙄
These two were maintained as they were so that comparison verification could be performed if there was a problem on the platform side. Or, if the user notices something unusual, the other one can be used as a replacement 😉
RHEL + Oracle dominates Java projects in Japan. For this reason, RHEL-based distributions are relatively popular among engineers and students.
- Users may want to use the distribution they are familiar with ..?
- I think some people will start learning Linux as a result of self-hosting. Therefore, I had wanted to have a RHEL series distribution as one of my options.