[Feature Request] Add flag options to disable "local" sites

[robotsox]

Hi,

Please add a new configuration flag, e.g. allow_local_sites, to control whether users are allowed to create local sites within an organization.
When set to false, users should be prevented from creating new local sites.

Thanks!

[miloschwartz]

Latest version should have flags.disable_local_sites, though not in the docs yet because it's for testing. You can also use flags.disable_basic_wireguard_sites

[robotsox]

Nice, thanks!