[Feat]: add OpenRC support

[akr2002]

What is your suggestion?

Theoretically it should be possible to install code-server on any machine that supports npm and yarn.

Currently the docs only cover installation of code-server on systemd-based distributions, with the exception of Termux. While writing an OpenRC script is trivial, the user is required to edit it in order to get it working under the user's permissions rather than root.

Why do you want this feature?

I want to run it on non-systemd distros.

Are there any workarounds to get this functionality today?

Install manually and write an OpenRC script.

Are you interested in submitting a PR for this?

Yep. I managed to run it on Artix Linux. Expect a PR soon.