Add option to not activate connection immediately

[jcronenberg]

Currently when we run

agama/rust/agama-migrate-wicked/src/migrate.rs

Line 38 in 813a755

nm.write(&state)?;

the following line is always executed

agama/rust/agama-dbus-server/src/network/nm/client.rs

Line 102 in 813a755

self.activate_connection(path).await?;

But because the migration is supposed to often be run from a container where the interfaces aren't available an error
[ERROR] Could not add/update the connection en0: D-Bus service error
gets logged even though everything else went well. (See e.g. our integration testsuite)

To avoid this I see 2 possibilities:

• add a flag inside the network model if the connection should be activated or not
• modify the write() and add_or_update_connection() functions to take a parameter if connections should be activated or not