Add support for macos

[ovo-Tim]

Hi, it's such a nice project. 🤗

As the title suggests, would you mind me adding macOS support to this project? Though I hate macOS, I have to use it at work. This project is a perfect solution to provide a Linux environment. The current roadblock seem to only be the landlock, and I could use conditional compiling to disable this. If this looks good to you, I can open a PR.

[Gerharddc]

Since Litterbox heavily relies on various Linux features, I imagine that the experience/functionality on macOS will be severely degraded. However, if it still offers value despite that, I don't mind integrating support.

Unfortunately I do not have a macOS machine and have no motivation to work on support for it at the moment. Hence, macOS support would have to be labeled as "experimental" and "not officially supported" for now.

I imagine the biggest missing feature right now will be support for graphical applications since that relies on passing in a Wayland socket on Linux. In theory, https://github.com/J-x-Z/cocoa-way plus https://docs.mesa3d.org/drivers/kosmickrisp.html could be leveraged to make this work on macOS, but that would likely require tremendous effort.

Without graphical support, it will not be possible to run graphical editors inside a Litterbox which is something you would ideally want to do. But I guess that won't be a problem for people using terminal editors and working on non-graphical applications.

Anyway, many thanks for the PR @ovo-Tim ! I will review it as soon as I get a chance.

[Gerharddc]

For the reasons stated in #96 (comment), it just does not make sense to try and support macOS with the current incarnation of Litterbox. Should there ever be an incarnation based on microVMs, then this could become quite reasonable.

Once again, my apologies for taking so long to reach this conclusion and thanks again for the effort you put into trying to make this work.