chore(assetcard,avatar,badge): remove mdx files (#3408)

* docs(assetcard): remove MDX file

- adds some missing documentation regarding stories, classes and custom
properties
- corrects sentence-casing of story names

* docs(avatar): remove MDX file

- adds some missing documentation regarding stories
- reorganizes some information to sit with appropriate story/variant
- migrates documentation from MDX file to the stories file instead

* chore(avatar): fix disabled test arguments

* docs(badge): remove MDX file

- adds notice badge variants to semantic story
- adds sizing story to docs page
- migrates documentation in MDX to stories.js instead

* docs(badge): pr fixes

- remove empty doc block line
- remove html wrapper in favor of content array
- add notice badge to test coverage

Author: marissahuysentruyt

components/badge/stories/badge.stories.js

@@ -1,3 +1,4 @@
+import { Sizes } from "@spectrum-css/preview/decorators/utilities.js";
 import { default as IconStories } from "@spectrum-css/icon/stories/icon.stories.js";
 import { ArgGrid } from "@spectrum-css/preview/decorators";
 import { Sizes } from "@spectrum-css/preview/decorators/utilities.js";

components/badge/stories/template.js

@@ -1,3 +1,4 @@
+import { Container } from "@spectrum-css/preview/decorators";
 import { Template as Icon } from "@spectrum-css/icon/stories/template.js";
 import { Container, getRandomId } from "@spectrum-css/preview/decorators";
 import { html } from "lit";