Make a decision on chdir support

[jaybosamiya-ms]

The core LiteBox crate itself internally maintains (in some of its file systems) a notion of cwd, but it does not actually expose a chdir or similar, since the cwd support is not fully matured. For now, #692 is introducing chdir at the shim layer, but we need to think about whether some version of this should be at the LiteBox layer, or if we want to just rip out the cwd support inside LiteBox entirely.

[jaybosamiya-ms]

Broader question to consider: should be actually separate out path handling as its own thing. It might simplify some of the commonality between the various LiteBox file systems.