Render Collapsible Blocks from Markdown

[ribbal]

Related issue

Fixes the items in this discussion: #1344

What changed

Extended the shoutout block parser to render collapsible blocks. Here is some example markdown:

:::collapsible Collapsible Block
_Formatted Content!_
:::

:::collapsed Collapsed Block
Hidden content!
:::

:::info
Info text
:::

Checklist

• I discussed the approach on the linked issue before starting (or this is a trivial fix: typo, docs, obvious one-liner)
• This PR is focused on a single change
• I ran npm run format in ui/leafwiki-ui (and in e2e if e2e tests changed)
• I updated documentation if needed