Support Web Components

Web Components are an interesting use case. Because of the browser-enforced scoping and encapsulation via the shadow DOM, it may be possible to do even better analysis than we do for normal components. Those constraints may open the door for [hierarchical analysis and optimizations](https://github.com/linkedin/opticss/issues/19).

It would be interesting to explore what a CSS Blocks integration for web components would look like.

* What would the syntax be?
* How are blocks associated to a web component template?
* Does it make more sense to do a generic analysis and only optimize with opticss (bypassing CSS Blocks altogether)?

cc: @morewry

Start by reviewing the issue's questions about syntax, associating blocks with web component templates, and whether to use generic analysis or CSS Blocks. The issue names no files, tests, or entry points; done would require a decided integration design and a documented path forward.

Written by the indexing model from the issue text.