RTE Blocks: Improve UI to show options to delete, edit, duplicate

[al3ks]

In the backoffice, when you are editing a content node, you can add Blocks to the RTE, just like you could do with macros in the older versions. Once a block is added to the RTE there are no visual options for managing that block. To improve the editor experience it would be great to add options to the side of the block to allow to easily delete, edit or duplicate the block just like we have for block list items. The same could apply to elements such as embedded videos, media items and tables within the RTE.