By default, do not show channels in the channel mgr (overview) for which the cms user does not at least have privilege 'hippo:channel-webviewer'

In the channel mgr, by default we show channels for which the cms user at least can read the documents : The user should passs

userSession.nodeExists(channel.getContentRoot())

However, if the CMS user does not have the privilege hippo:channel-webviewer on the corresponding hst:configuration node of the channel, the Channel Mgr won't function properly (the cms user shouldn't have access to the channel in the channel mgr since it does not have the required privilege resulting in most endpoints not being allowed for the user, see HSTTWO-4653

Hence, by default, we should also skip channels in the channel mgr (overview) for which the cms user does not at least have role hippo:channel-webviewer

Note: Next to the channel mgr not showing the channels for which the cms user does not have privilege hippo:channel-webviewer, of course the channels should not be shown in something like the [view] tab for documents, or in downstream projects like relevance or projects feature