Cerberus support

[vzaliva]

Now, as compiler-explorer/compiler-explorer#5864 have been merged (Thanks!), I want to add support from Cerberus to the main website.

@mattgodbolt wrote: "The process could do with a look at: but basically if you have a system that can install the compiler from a tarball, or a dockerfile that can bulid it for Ubuntu 20 or 22, then we can help :) The compiler needs to be able to be somewhat hermetically built with no external dependencies (or minimal) as it will be run in a very restricted environment. Let me know if I can help more!"

We do not presently have a tarball, but we have a very simple ubuntu-based docker container:

1. Dockerhub
2. Dockerfile

As you can see, the installation is done via OPAM package manger, which is, in turn, provided by Ubuntu (and other distros). Theoretically one can make OPAM to install everything under /opt or any other location by providing --root=/opt/compiler-explorer/.opam command line option to opam init command.

I am volunteering to do what's needed but need some guidance.