Support to stop rendering a Plugin in case the Plugin itself 'knows' that it shouldn't be drawn

Currently, the PluginManager starts plugins from

 public PluginContext start(IPluginConfig config) {
        final PluginContext context = new PluginContext(this, config);
        IPlugin plugin = factory.createPlugin(context, config);
        if (plugin != null) {
            context.connect(plugin);
            return context;
        } else {
            context.stop();
            return null;
        }
    }

which invokes org.hippoecm.frontend.plugin.impl.PluginFactory#createPlugin

Now, if the plugin to be created, for example a 'FolderTreePlugin' (the drop down in the content editor for 'documents', 'gallery', 'assets', etc) finds out that the user is not allowed to read the right content (for example not allowed to read /content/gallery), then instead of logging a warning that /content/gallery does not exist and adding the 'Gallery' plugin to the drop down, it should just skip that plugin from the dropdown

However currently, a plugin cannot during its creation throw some exception to gracefully short-circuit it being rendered without being logged as a warning or error