Multiline text view for viewing completion results

[robatwilliams]

The Excel formula bar is useful for viewing long formulas or long static text, without needing to adjust the cell size in the spreadsheet layout. There isn't however a way of viewing long formula results (i.e. chat completions).

We've implemented a basic solution via the _lines property of the custom entity, which shows up in the entity card (that can be resized, but doesn't remember it's size). This still isn't ideal.

Perhaps we could do something in the sidebar.