docker: Change Settings to single owner

We change DockerSettings to have a single owner.
Since DockerDevices are destroyed after the plugin
is unloaded, we have to make sure to remove the
settings from devices during plugin teardown.

For this we store a list of created devices in
the factory, and call their shutdown function when
the plugin unloads.

Change-Id: Ic9c7d8ad9437c48d68f20c9a8f8ad7449b3cb972
Reviewed-by: hjk <hjk@qt.io>

src/plugins/docker/dockerapi.cpp

@@ -43,7 +43,7 @@ using namespace Utils;
 
 DockerApi *s_instance{nullptr};
 
-DockerApi::DockerApi(QSharedPointer<DockerSettings> settings)
+DockerApi::DockerApi(DockerSettings *settings)
     : m_settings(settings)
 {
     s_instance = this;