Blender Git Loki

Allow asset engines to change current dir also from list_dir function.

Rational is, in case of online repo, it may not be practical to decide
whether a path is valid or not from check_dir() callback, which should return
immediately.

So instead, check_dir() can only check whether path **looks** good, and
delegate actual path validation to list_dir (and maybe other similar functions).

That?s what is being tested with Claude engine at least.