[Dev UI] Improve scrolling of nested containers for flow runner, and others

[MichaelDoyle]

Suggestions:

1. Use expandable outputs in lieu of scrolling ones
2. Consolidate streamed and non-streamed responses into one section, w/o an inner scrollbar, and optionally continue to scroll down as responses are appended

Via @apascal07:

In the Run tab, we have 2 containers, one for input, one for output. Both scrollable, with the larger container that contains them both scrollable. Input, if not large enough, is not scrollable but prevents the scrolling of the larger container. Hover mouse over center area between input/output allows scrolling of larger container... until mouse hits output container at which point it starts scrolling that.

It's actually even worse than that, there are 2 boxes for output when streaming and... they're both scrollable. 3 nested scrollboxes with no visual discerning of where one ends and another begins