Automated testing of Netty's io_uring support

To make Netty's io_uring support more reliable, I created a Linux stable repo on GitLab to trigger automatic tests. Whenever there's a new (Git) tagged version in Linux, the following steps will run:

1. Build a kernel image
2. Start QEMU VM on that image
3. Run Netty's io_uring tests

Roadmap

• Add x86_64 netty test pipeline
• Add aarch64 netty test pipeline
• Run pipelines in parallel
• Integrate with Netty's io_uring repo

Why GitLab?

GitHub Actions currently requires the configuration file to live in the same repository as the project being tested, it's not suitable for mirrored repositories. GitLab CI/CD, on the other hand, allows external configuration files such as the one hosted in this repository.