Create "Current Node" block

Description of the need

We have an existing block NodeBlock that allows pointing at any arbitrary node as a block by its Node ID. I have a situation where the best way to use layouts may be to render the same node multiple times on the same page, each with different display modes. For example I have a banner area at the top of the page, as well as the main content area that is a wide column. I want to display a "banner" display mode in the banner area in addition to the "full page' display mode used in the main content block.

Proposed solution

Introduce NodeCurrentBlock class that can render the node. This block would have the required context of node so it would only show up on node/% path layouts (or other layouts with a Node context).