For some reason, on Windows, creating a directory with zero permissions
still allows creating a file in there. Just skip that part of the test.
The Explorer's properties panel of the directory also shows "Read Only
(only applies to files)", so at least that seems consistent.
This just updates the config and saves it to `flamenco-manager.yaml`.
Saving the configuration doesn't restart the Manager yet, that's for
another commit.
This adds a `-wizard` CLI option to the Manager, which opens a webbrowser
and shows the First-Time Wizard to aid in configuration of Flamenco.
This is work in progress. The wizard is just one page, and doesn't save
anything yet to the configuration.
