Support shell and/or instance executor

[lmilbaum]

Describe the solution you'd like

We have workflows which can only run on instances (not containers). For that we probably need to use the shell executor or the new experimental instance executor.
It would be super helpful to support it in this module.

Describe alternatives you've considered

The alternative is to find another module or implement one by myself

Suggest a solution

Additional context

[kayman-mk]

Any chance to get some insights why the jobs can't run in a container?

[lmilbaum]

Any chance to get some insights why the jobs can't run in a container?

Our product is an operating system. Building, deploying it and testing it requires special resources which are not available in container.

[kayman-mk]

Any chance to get a PR from you, @lmilbaum?

[lmilbaum]

I can start by breaking the effort into small PRs

[dsalaza4]

We would really love to have this as well.

We use Nix for pretty much everything in our organization.

By having support for the shell executor we would be able to create a custom workflow that takes complete advantage of all of Nix's capabilities.

Containers right now are a form of middleware for us required to be compatible with most tools out there.