Improve experience with long codeblocks in panel chat

[roblourens]

If I ask panel chat to generate some code in the panel, then I might get some long codeblocks and also some prose explanation of them. It's inconvenient to read these because the view is narrow and I'll have to scroll around a lot to see both the explanation and the code. It would be useful if the codeblock would actually open in an editor view in some cases so that I can read the code and the explanation side by side.

We could start rendering codeblocks inline, and when they get to a certain length, collapse them inline and start rendering them in a preview editor in the main editor area. Or, try to detect a scenario when the model will generate a bunch of code from scratch and use this mode in that scenario.