[Dev UI] Markdown Rendering

[MichaelDoyle]

If the model response returns markdown (or part of the response as markdown), typically quoted by "triple ticks", we should render it with the appropriate formatting. Some basic examples below.

Requirements

1. This applies anywhere we have model output.

   1. Model runner
   2. Prompt runner
   3. Flow runner

2. We should have a way to either view and/or copy the "plain" text.

e.g.) Plain

Markdown:

```
** Here is some markdown **
1. It's formatted really nice
1. And it renders a list
1. So much wow
```

Rendered:

Here is some markdown

1. It's formatted really nice
2. And it renders a list
3. So much wow

e.g.) Code

Markdown:

```js
console.log('hello world')
```

Rendered:

console.log('hello world')

[mjchristy]

What do we think about trace viewer? Is JSON still more appropriate there.

[pavelgj]

What do we think about trace viewer? Is JSON still more appropriate there.

looks it's covered by #1553