Draft: implement copy link trailing action in groups and channels

This MR will implement the option to copy a messages link so it can be posted in another chat, e.g. a direct link to a FAQ post.

This option will be added to the trailing action of a message. The stock-link icon is used. This option is only possible in public groups and channels. Otherwise the link would not be accessible for users. And only where a group has got a proper group name set, not just a title.