Document how to use plugins in the Web Component guide

[RayBB]

Guide: https://vuejs.org/guide/extras/web-components.html

In short, it would be great to add information here about how to use Vue plugins when building Web Components.

It was a headache to figure this out and I ended up going with an external dependency vue-web-component-wrapper.

It would be nice if the guide mentioned this dependency or even provided a way to use plugins without a dependency.

I wrote about this and more on my blog: https://blog.rayberger.org/vue-3-web-components-open-library