Blender Git Loki

Fix race condition when multiple file/asset-lists are running at once

E.g. opening a file with an asset viewer and an Asset Browser could cause one
of them to not load its files properly. That is because there was only one
`wmJob` per scene so when the first one was done it would end the other one(s).
I think this would be a problem in master for the regular File Browser too.

Instead of setting the scene as owner of the job, use the file-list, so that
each file/asset-list gets its own job.