VMs: persist state folders on host

Done:
- move vm inspect attrs from system.clan.vm.config to clanCore.vm.inspect. This gives us proper name and type checking. everything in `system` is basically freeform, so the previous option definitions were never enforced
- when running VMs, mount state directory from ~/.config/clan/vmstate/{...} from the host to /var/vmstate inside the vm
- create bind mount inside the VM from /var/vmstate/{folder} to / for all folders defined in clanCore.state.<name>.folders

TODOs:
- make sure directories in ~/.config/clan/vmstate never collide (include hash of clan-url, etc.)
- port impure test to python

pkgs/clan-cli/clan_cli/vms/inspect.py

@@ -25,7 +25,7 @@ def inspect_vm(flake_url: str | Path, flake_attr: str) -> VmConfig:
 
     cmd = nix_eval(
         [
-            f'{flake_url}#clanInternals.machines."{system}"."{flake_attr}".config.system.clan.vm.config'
+            f'{flake_url}#clanInternals.machines."{system}"."{flake_attr}".config.clanCore.vm.inspect'
         ]
     )