Feature Request: Add CSS and JS Options Per-Block Template

Currently, we can include JS and CSS for block templates in <style> and <script> tags, of course. And I know and have used the this.block.add_css() method before.

But, can we have an option those separate from the UTL, but still scoped within the block (sort of like Vue files). Here's an example screenshot:

..so anything in "Block JavaScript" would be in the page (inline or script), and the CSS within this.block.add_css()