[UX] Design new comment button and unfurling behaviour

[jonbell-lot23]

We'll be putting this in several places in the app:

• Network Monitor (a few different panes)
• Comment pane
• Print statement
• Maybe others, stand by

We need to consider some other stuff, like:

• How should it look when it's disabled?
• Jason had an idea to remove the button entirely from print statements if not paused
• We're also thinking about more contextual stuff, how does this play with that?

[jonbell-lot23]

This is in a good place for now, design-wise. Closing out