feat: ui.markdown component

[wusteven815]

• Adds ui.markdown widget #890
• Update Jest transform (similar to feat: add LaTeX to Markdown web-client-ui#1734 (comment))

[dsmmcken]

Would we expect it to accept common props as well?

[dsmmcken]

For reference: https://docs.streamlit.io/develop/api-reference/text/st.markdown#stmarkdown

Streamlit exposes unsafe_allow_html to turn off escaping.

Also supports emoji shortcodes which is just neat. Probably not something we need to do, but neat.

[mofojed]

Code blocks aren't rendering properly. You'll need to pass in a component for rendering code blocks, like we do in our MarkdownEditor component.

ReactMarkdown shows an example of this in their page as well (side note, I didn't know you could use tildes to mark code blocks as well, thought it was just backticks).

Example that doesn't look right:

from deephaven import ui

md = ui.markdown("""
# Code block example

```python
from deephaven import empty_table
t = empty_table(1000).update("x=i")
```
""")

Added

[dsmmcken]

Looking good. Add doc page.

Added