Adds markdown-it-container support to VS Code.
Input
::: tip
This is a _tip_
:::
::: details
This is a details block
:::Output
This is a tip
Details
This is a details block
Output (HTML)
<div class="tip">
<p>This is a <em>tip</em></p>
</div>
<details>
<summary>Details</summary>
<p>This is a details block</p>
</details>