The electron app doesn't start up the app-server in a particular
workspace directory.
So sandbox setup happens in the app-installed directory instead of the
project workspace.
This allows the app do specify the workspace cwd so that the sandbox
setup actually sets up the ACLs instead of exiting fast and then having
the first shell command be slow.
app-server support for initiating Windows sandbox setup.
server responds quickly to setup request and makes a future RPC call
back to client when the setup finishes.
The TUI implementation is unaffected but in a future PR I'll update the
TUI to use the shared setup helper
(`windows_sandbox.run_windows_sandbox_setup`)