[6.x] Fixed bad dependency assumptions

[GrahamCampbell]

1. The scheduler uses the native container (and not the contract), and so we must ensure that it is recommended to users both by composer, and by friendly runtime exceptions. If we wanna refactor it to use the contract, that is a job for the master branch.
2. We should not be calling stuff from the foundation helper functions file. We should instead be resolving the jobs and the job dispatcher from the container, and providing good developer experience if we fail to resolve it. Removal of the calls to the foundation functions also made it clear we actually had an dependency on illuminate/queue too, for packing Closures.

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Closes #31891.

[wonderlandzor]

I opened the issue to start a disccusion, but this works too. Wouldn't injecting an implementation of Illuminate\Contracts\Container\Container be way easier instead of dynamically checking if an instance can be resolved? Right now you're adding illuminate\container as an optional dependency, but in reality this whole class doesn't work without it being available.

This is by no means meant as critique, it just doesn't match the approach I had in mind, so I'm trying to follow your thought process here.

Also please let me know if I can be of any help in this, I was originally planning on opening a PR after gathering some thoughts on the issue, but I'm more than happy to help out here instead.

[GrahamCampbell]

I opened the issue to start a disccusion, but this works too. Wouldn't injecting an implementation of Illuminate\Contracts\Container\Container be way easier instead of dynamically checking if an instance can be resolved?

We have no means of doing that without having a container, and even if we could, as I said, that would fall out of the remit of a bug fix. Such a refactoring would have to target the master branch.