Plugin owns the object and callers must reference it if they wish to use it outside
of the function they called "add" from. Likewise, callers of the ConnectionProvider's
add_connection method must also reference the returned object if they wish to
continue using it.
Add a "monitor-connection-files" config option, which can be set to
"false" to disable automatic reloading of connections on file change.
To go with this, add a new ReloadConnections method on
o.fd.NM.Settings that can be used to manually reload connections, and
add an nm-cli command to call it.
We don't always want to immediately write new connections to disk, to
facilitate "runtime" or "temporary" connections where an interface's
runtime config isn't backed by on-disk config. Also, just because
an interface's configuration is changed doesn't necessarily mean
that new configuration should be written to disk either.
Add D-Bus methods for adding new connections and for updating existing
connections that don't immediately save the connection to disk.
Also add infrastructure to indicate to plugins that the new connection
shouldn't be immediately saved if the connection was added with the
new method.
