Add Flatcar OS support

[HoKim98]

Hello, first of all, thank you to those who lead such a great project.

Added Dockerfile and installation script to use ofed-docker Docker image in Flatcar Container Linux. Unlike other major Linux distributions, the kernel source code and build process in Flatcar Linux work similarly to Gentoo, so the installation script is slightly different, but the main functions are the same.

How to Build

Same as for other OS's.

docker build --tag ofed-driver:latest ./flatcar

How to Run

Since the /lib directory is read-only on Flatcar Linux, mounting the host directory does not change anything. However, general application is possible in a state where changes can be made, such as overlaying the /lib directory.

Made compatible with mofed Pod in network-operator provided through Helm in Kubernetes.

docker run -it --name mofed \
     --privileged --net host --ipc host \
     --volume /etc:/host/etc \
     --volume /lib:/host/lib \
     --tmpfs /tmp --tmpfs /run \
     ofed-driver:latest