We already have Update(), UpdateUnsaved() and Save(), which serve
similar purposes. We will need a form of update with another argument.

Most notably, to block autoconnect while doing the update.

Other use cases could be to prevent reapplying connection.zone and
connection.metered, to to reapply all changes.

Instead of adding a specific update function that only serves that
new use-case, add a extensible Update2() function. It can be extended
to cope with future variants of update.