create more robust "+N with modal" component, use in External IPs on instance page

We have a pattern we're able to use with the <ListPlusCell> component, where we roll up some arbitrary number of extra items into a tooltip. We need to have a similar component we can use when the contents of the roll-up need to be interactive. Accessibility rules dictate that an interactive element (like a button or a link) can't be nested inside another interactive element (like a tooltip or other visible-on-hover element).

One place where we can use this is in the Instance page's header, where we list the External IPs, each with a link and a click-to-copy button. We should be able to list some number (2–3), with a +4 (or whatever) button that opens a modal listing the other IPs.

Start by reading the existing component and the Instance page header where External IPs are displayed. Trace how the links and click-to-copy buttons are rendered, then verify that the new reusable pattern shows a small set of IPs and opens the remaining interactive items in a modal without nested interactive elements.